OK, I am going to go through and try to say something positive and something negative about each submission.
Note 1: This is just the first half. This took longer than I thought.
Note 2: A lot of cards give you VP tokens contingent on buying/gaining/possessing Victory cards. I don't like that. What I've always liked about VP tokens is that they are one way of enabling greenless decks. If I'm still going to be buying green cards, I'd rather have new alt VP card.
Note 3: As to be expected, a lot of these cards appear to just have vanilla bonuses tacked on or numbers inflated to have a high cost, presumably to fulfill the "spendy" theme. I feel like that is misguided. Prosperity is a place to put interesting cards which just happen to be expensive. If you have a cool idea, but the idea does not justify a $7 price tag, then save it for a different set. Piling on the vanilla probably won't do the trick.
Relic
Types: Treasure
Cost: $6
Worth $2. When you play this, you may trash up to 2 cards from your hand and play area. If you trashed at least one Action card, +$2 and +1 VP.
Good: I like that it incentivizes trashing a good card (e.g. an Action).
Bad: Seems really strong to me. I'd probably buy this even if I could only trash a single card, with no potential bonus for trashing an Action. I'm afraid that trashing from the play area would be confusing, but Procession and Counterfeit already do it.
Artist
Types: Action
Cost: $6
+$3. You may trash this. If you do, the first time you buy a Victory card this turn, +3 VP.
While this is in play, when you buy a Victory card, +1 VP.
Good: I like the option is get a larger bonus by trashing.
Bad: I already want to buy Victory cards, usually. I'd prefer that VP tokens give me an alternative to greening, not further incentivize it.
Usurer
Types: Action
Cost: $6
+1 Card. +1 Action. Reveal cards from your deck until you reveal a Treasure. Discard the rest. Trash the Treausre; gain a Treasure costing up to $3 more than it, putting it on top of your deck. Each other player may gain a Copper, putting it into his hand.
Good: Nice fit for Platinum games, where you can really breathe life into your early Silvers. I wondered about the need for the +1 Card, but I suppose it causes you to scoop up your upgraded Treasures as you play multiple Usurers.
Bad: Maybe too fast? I wonder how a Usurer rush would compare with Rebuild. I guess Rebuild depletes the Duchy pile, which is a huge strategical difference.
Treasure Chest
Types: Treasure
Cost: $4
Worth $1. When you play this, discard the top card of your deck. If it is a Treasure, gain a Silver
Good: Seems like a cool Silver gainer. The more Silver you have, the more likely Treasure Chest is to give you more.
Bad: Silver isn't so great in Colony games, making this a bit awkward in Prosperity. "Gain a Treasure costing less $6" would help it fit in by giving it more synergy with Prosperity's alt Treasures. If you are worried about cost reduction giving you Gold, you could even say "costing less than Gold."
Strong Room
Types: Action
Cost: $5
+4 Cards. +1 Action. You may return up to 4 VP tokens. Discard 4 cards, minus 1 card per VP token returned.
In games using this, at the beginning of each turn of the player who went first, each player gets +1 VP.
Good: It's already sort of nice just as a bigger Warehouse.
Bad: I don't like the focus on the first player, since it makes the first player's decision to play Outpost or the last player's decision to play Possession have an outsized impact on the game. I think just getting a token at the start of your turn might be better. It intensifies first player advantage a little, but the card on the whole appears to make single point differences less significant.
Metropolis
Types: Action
Cost: $7
+1 Card. +2 Actions. Treasure cards other than Copper produce an extra $1 this turn.
Good: At first I thought that this would be too similar to Bank, but now I see it as a way for an engine to squeeze the most value out of a small number of Treasures. Especially nice with Loan, Quarry, or Potion.
Bad: Village + Cash feels a little boring for $7. I wonder about whether it is balanced.
Stock Exchange
Types: Treasure
Cost: $7
Worth $2.
While this is in play, when you buy a Victory card, you may buy any number of VP tokens for $1 per token.
Good:
Bad: Pretty much removes any distinction between buying Estate, Duchy, or Province when you have $8 in hand. I mentioned this before, but I want VP tokens to provide an alternative to greening.
Chalice
Types: Treasure
Cost: $4
Worth $3.
While this is in play, when you buy a Treasure card gain 2 Coppers, when you buy a Victory card gain a Curse.
Good: I like that this encourages an engine.
Bad: Feels a little bit similar to Quarry, except that Quarry rewards me for buying Actions rather than punishing for buying something else. Rewards are usually more fun. Also, it feels a bit like Contraband, in that it makes buying Gold and Province more difficult. Curses are often empty by the time you start greening.
Surveyor
Types: Action
Cost: $5
+1 Card. +1 Action. +$1. You may reveal a Province or Colony from your hand. If you do, +1 VP. You may return 3 VP to the supply. If you do, gain a Province.
Good: Seems to support a new sort of deck where after your first Province you continue to profit off of them, earning more to fuel further expansion without ever needing to hit $8 a second time.
Bad: I wouldn't bother mentioning Colony. Most games don't have them, and the 1 VP is less significant in Colony games anyhow. This card is about snowballing your Provinces.
Gilded Statue
Types: Treasure
Cost: $7
Worth $2. When you play this, you may discard a Treasure. If you do, gain a Gold.
When you gain this, gain an Action card costing up to $4.
Good: I like the Gold gaining mechanism.
Bad: I don't like the when-gain clause. Sometimes that card will be Smithy or Envoy and this card will be nuts. Othertimes it will just be some junky action or nothing at all. I don't think this card needs it either; maybe just price this at $6?
Railway Town
Types: Action
Cost: $6
+1 Card. +2 Actions. +$1. If you have played railway town at least twice this turn, +1 Buy. If you have played it at least three times this turn, +1 VP. If you have played it at least four times this turn, +$1. If you have played it at least five times this turn, +1 Card.
Good:
Bad: Too much going on. In a four player game, when are you ever going to get a fifth play in? Even in a two player game, just pummeling this pile is going to determine too many games. If I win the split 6-4, then I gain 4 VP each round while you gain just 2 VP.
Charity (A)
Types: Treasure
Cost: $7
Worth $4. +1 Buy.
While this is in play, when you buy a card, each other player gains a card costing at most $2 less than it.
Good: I like this card. I like that the price point gives your opponents the option of a $5 when you buy another Charity.
Bad: I don't think it needs the buy. I think that gain should be optional rather than forced. It is supposed to be a penalty, right? Well currently you use it to buy engine pieces while junking your opponents. The +buy only exacerbates that.
Wedding
Types: Action
Cost: $7
+1 Action. Reveal cards from the top you your deck until you reveal an Action card, a Treasure card and a Victory card. If you do reveal a card of each of these types, put an Action card, a Treasure card and a Victory card from among the revealed cards into you hand. Discard the other revealed cards.
Good: I like the idea of getting one of each.
Bad: Seems too expensive. I'd rather it be nonterminal, since the action is so time consuming. Also, it is confusing with dual type cards. What happens if the first two cards I reveal are Harem and Nobles? I would stop there and put both in my hands? What if I revealed Gold, then Harem, then Nobles? I suppose first I would have to put Nobles in my hand. Then I could choose either Harem or Gold. If I chose Harem, then I would discard Gold. I if I chose Gold, then I would keep Harem too? I guess it isn't so bad if you just run through the phrasing literally.
Palace
Types: Action
Cost: $4
+1 Buy. +$1.
While this is in play, during the Buy phase, Colonies cost $2 less, but not less than $0. While this is in play, when you buy a Platinum, +2 VP.
Setup: Add Colony and Platinum to the Supply.
Good:
Bad: I don't want to always have Colony and Platinum. Also, when Colony and Platinum are present, I already want them. This card just incentivizes them even more explicitly, at the detriment of competing strategies.
Crown (A)
Types: Treasure
Cost: $8*
Worth $1. When you play this, gain 2 Treasure cards.
During your turn, this costs $1 less per 2 VP chips you have.
When you gain this, +2 VP.
Good: Certainly encourages a heavily Treasure filled deck. Those might be some fun games.
Bad: That first one would be pricey, but that Crown could be used to gain more Crowns and then quickly deplete the Platinum pile. Or Harem, Gold, Philosopher's Stone, etc. OK, maybe this is not so bad after all.
Cathedral
Types: Action
Cost: $7
Gain two action cards costing less than this and a Gold.
Good:
Bad: This just seems way too strong.
King's Greed
Types: Action
Cost: $10
Put your deck into your discard pile. Look through your discard pile and set aside up to 3 Action cards from it. Play them in any order.
Good:
Bad: Seems way too strong. Giving it a huge price tag doesn't help that. It needs to be way cheaper while having some sort of penalty to keep it in check.
Mediator
Types: Action – Reaction
Cost: $3
+$3. Reveal 3 cards from your hand. The player to your left selects one of them. Discard it or put it on top of your deck.
When another player plays an Attack, you may set this aside from your hand. If you do, +1 Card, +1 VP, and at the start of your next turn, discard this.
Good: The reaction is interesting.
Bad: The terminal gold on a $3 card seems too strong. Also, there are lots of choices being made here. Choose three cards to reveal, then the opponent selects one, then you have to decide to topdeck or discard. I say just force the last step to be "discard", and then the first two decisions will be easier too. Or am I missing something?
Prospector
Types: Action
Cost: $4
+1 Buy. Reveal the top 4 cards of your deck. Put the revealed Treasure cards into your hand. Discard the rest. Each other player may discard a Treasure. If he does, he draws a card.
Good: I love how thematic the name is! Also, I like a nice big money card from time to time
Bad: Probably too strong for big money? Perhaps give your opponent an opportunity to discard a non-Treasure rather than Treasure. That would be the bigger boon to your opponent on a Prospector board, I'd say.
Jeweller
Types: Action
Cost: $6
+2 VP. Gain a Gold.
Good: Nice and simple. The Gold gaining keeps you from just pounding the Jewellers every turn for points, and and encourages you to start buying Provinces.
Bad: Maybe a tad boring?
Hunter
Types: Action
Cost: $6
Trash any number of cards from your hand. For each card you trash, +1 Card and +$1.
Good: You won't be able to afford to open with this trasher, so the bonuses help to make it worthwhile.
Bad: Too expensive to open with, which really hurts a trasher.
Forum
Types: Action
Cost: $5
Draw until you have 6 cards in hand.
While this is in play, when you play a Silver, you may trash that Silver. If you do, +1 VP.
Good: Those early Silvers sometimes hurt later on in a Colony game or just an engine game. This might help.
Bad: The +1 VP won't help so much in a Colony game. The on-play effect is very weak. Watchtower already does that at $3, and has an awesome and flexible reaction at the same time. I don't usually have all that much Silver that I want to trash.
Statue
Types: Action
Cost: $7
Discard up to 3 cards from your hand. +1 VP per card discarded.
Good:
Bad: This encourages just drawing your deck and then discarding it all without buying anything or advancing the game state. So broken with Scrying Pool!
Aqueduct (A)
Types: Action
Cost: $7
+2 Buys. +$2. Reveal the top 4 cards of your deck. Put the revealed Treasure cards into your hand and discard the rest.
Good:
Bad: This is really similar to Prospector (above), but more powerful and more expensive. I like Prospector a lot more. I feel like this one was just buffed up to get the cost higher, since Prosperity has a "spendy" theme.
Deed
Types: Treasure – Reaction
Cost: $5
Worth $2
When you gain a Victory card, you may discard this from your hand. If you do, +2 VP.
Good:
Bad: What's with all these cards that give you more points when you green?
Philanthropist
Types: Action
Cost: $4
+3 VP. Each other player gains a card costing up to $5.
Good: This one is pretty interesting. Not really sure how it would play out. It would be weak early on when you'd rather be building your engine. Later on your opponents could at least take a Duchy to keep up in points.
Bad: