please don't replace trade tokens...
I don't plan to. Polk5440 was just suggesting that there might be a simpler way to implement Jubilee specifically, and that Trade tokens should be reserved for "get one when you gain a card, spend it when you play the card for a bonus" effects. As I outlined, I disagree that Jubilee can be made simpler. Whether or not Jubilee is worth doing in general is another topic, but it's been quite popular in most of our playtests.
If you need 25 cards, and some might be replaced, may I suggest some cards?:
Cardinal: $4
+1 card +1 action. Gain a trade token. Each other player discards a Trade token.
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Court: $3
+1 card +1 buy. Count your Trade tokens. +1 coin per Trade token. Spend a Trade token. If you do, +2 coins.
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Camp: $4
+2 coins. Gain a Trade token. When another player plays an Attack card, reveal this from your hand. If you do, gain a Trade token.
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Trader: $4
Spend two Trade tokens. If you do, gain a card costing up to $5. You may overpay for this card. For each $1 you overpay, take a Trade token.
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Road: $5
+1 card +1 action. Trash a card from your hand costing $5 or more other then a Road. If you do, +3 coins.
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Bakery: $5
Trash this card. If you do, choose one: +2 coins on this turn and the next; take two Trade tokens; or +2 cards +1 action.
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Seamstress: $4
+1 card +1 action. Each other player gives you a Trade token; or reveals that they have no Trade tokens.
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Circus: $5
Trash this card and spend a Trade token. If you do, +3 coins +1 buy.
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Coat or Arms: $5.
$1. You may spend a Trade token. If you do, each Treasure in your hand produces +1 this turn and +1 buy. When you gain this, gain a Trade token.
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Museum: $3
Worth 2VP for every unspent Trade tokens at the end of the game.
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Theater: $4.
+2 cards +1. When you gain this, gain a Trade token.
Do you like them?
While I appreciate the thought, Awaclus and Archetype have nailed down the problem with most of your cards. Any Trade token card may be the only one in a given game, so each one must both give you Trade tokens and give you a use for them. But that doesn't necessarily mean that your post is devoid of good ideas; some of these effects could be made into cool cards. I'll try to talk about mechanics, rather than specific cards.
Attack that makes players lose Trade tokens: Cardinal and Seamstress do this. The problem here is that other players can easily avoid the attack by not buying Trade token cards. This in turn means that these Attack cards themselves won't get bought. So it would likely result in a lot of dead cards on the table, which is never ideal.
Play effect that gets better as you accumulate Trade tokens: Court does this. I think it's a mechanic with some potential. The key is that you have to spend at least one Trade token every time you get the effect that counts tokens (which Court does). Otherwise you're eventually going to get ridiculously powerful effects. (I suppose Pirate Ship does this, but still.) Also, such a card almost has to be able to get Trade tokens when played. If you only get them when you gain the cards, eventually they dwindle down to uselessness, at which point you might as well trash those cards. Craftsman kind of already does this, but there you have to actually
spend more tokens to get the larger effect. I think there may be a good card somewhere in this space of 'better when you have more tokens'.
Victory card that counts Trade tokens: Museum does this. This concept I'm not so hot on. If it's the only Trade token card in the game and you get tokens when you gain it, it basically counts itself. Donald tried that and it eventually turned into Duke. It might be possible that instead of gaining tokens when you gain the Victory card, it's also an Action or Reaction that gains tokens, but I don't love that either. For one thing, VP tokens (from Prosperity) do this more elegantly. For another, I generally want players to spend their Trade tokens to get cool effects. When one card says, "Hoard all your tokens," it works against all the other Trade token cards on the board.
Reaction that makes Trade tokens: Camp does this. This could work if stapled to an Action card that uses the tokens. If Recruiter doesn't work out, I may try something like this.
Trash a card costing at least $X for a big benefit: Road does this. I don't think the threshold (saying "a card costing at least $5") is a great idea. Cards that trash a card for a scaling benefit depending on the cost of the card (Trader [from Hinterlands], Bishop, Apprentice, Salvager, etc.) are nice because you can use them on Estates early on and then you can choose to use them on expensive cards later for big effects. Something about having to trash a really expensive card to get any sort of benefit turns me off. It seems like it wouldn't be a popular buy.
Expensive one-shot that gives one of several powerful options: Bakery does this. Generally, if I'm going to have a choose-one ability, I want the choices to be related in some way, e.g. Gambler. I feel cards that are just a bunch of different options as their core ability is Intrigue's schtick, although it's fine to do them elsewhere (Count from Dark Ages). This isn't necessarily out of the question, but I don't find it super compelling.
Those are the big ones. Trader is "spend a few tokens to gain a $5 card", which Craftsman already covers. Circus is "trash a card and spend a Trade token for an effect", which is redundant once you factor in that the card needs to also gain tokens. On any board without other Trade token cards, it's basically just a normal one-shot. Coat of Arms's role is "spend a token for extra Coins and a Buy", which I feel Fund sufficiently fills. Once you factor in that a card needs to both spend and use tokens, Theater doesn't really have a concept at all.
That's it! I may very well try a card like Court or Camp, so I appreciate you taking the time to suggest these ideas.