EDIT: I didn't realize that there is only one copy of Bear Market/Bull Market. In that case, may I suggest:
If you don't have Bear Market or Bull Market, take it. Otherwise, flip it over.
This wouldn't work (or rather, this changes what the Event does), as the State is meant to be flipped every time. Who has the State when it's not being flipped does not matter, and taking it shouldn't cost an extra buy. I originally wanted it to just sit next to the Event, but the rules (as I read them) don't permit this.
I looked at Misery when I was doing the wording. My only concern with the way you have it is that it might be a bit confusing. It is not entirely clear that "Bull Market" and "Bear Market" are a single, two-sided State. Thus, it is not self-evident from the text what the "it" in "take it" or "flip it over" is. A player might go looking for the other Market, or think they have a choice.
Except for the first time this is bought, it is „convert 2 Buys into 1 Coins“.
That is the basic idea. It converts a Buy into $0.5 an unlimited number of times. There is a free half-buy for the first player to use this. While that introduces a little bit of swinginess, I don't think $1 is enough to force players to rush out and try to get it.
Unless the opponents have no extra Buys in their decks, you will never ever buy this only once in your turn and thus help your opponents.
Never EVER? Certainly not if you're dueling Market Squares, but there may be a lot of cases where you would consider it.
What if your opponent has only one +Buy in their deck. What if it's Skulk (and they have really good trashing)? Are they going to give up trashing their Skulk (or are they going to play one of the worst terminal actions, if they have other choices) just to steal $0.5? Are they going to eat an Estate from Baron for it? I would posit that 9 times out of 10 they will not. Similarly, if they would have otherwise used that spare Buy, it probably will not be worth trading for the coin (depending on the numbers).
Conversely, even if your opponent has no +Buys, if they draw an all-green hand they still have one buy that they can use to trash your half coin. That strategic choice--put the $0.5 out there where it might be stolen or let it go to waste--is the reason I settled on a single State, instead of one for each player (or the terrible ideas I had before that, like using the cubes from Projects or the Journey token).
The problem of this concept is that it is either too good or too weak. All the four (did I forget one?) cantrips that yield Buys become significantly better whereas it matters little for all other cards.
I count five (Market, Grand Marker, Market Square, Worker's Village [unless you consider this a village and not a cantrip], and Sanctuary), plus four marginal cases: Hamlet (you need to discard for the +Buy), Pawn (have to give up either the card or the action if you want the buy) Snowy Village (no more +Action potentially limits total plays) and City (only once 2+ supply piles are empty). With the exception of Market Square and Worker's Village, I don't see any of those cards being significantly improved by the presence of this card, or becoming must-buys.
Having Market or Grand Market go from +$1 to +$1.5 or +$2 to +2.5 is a pretty marginal change. Sanctuary's power is in the ability to Exile cards efficiently, gaining some extra coins does not change that significantly. Plus, buying a Sanctuary or two to at least mess with your opponent's residual 1/2 buy at the margins is not that likely to severely mess up strategies that would not otherwise be going for it, as the deck improvement they get from Exiling their VP cards would likely make up for it.
The marginal cases would similarly see little improvement, for the reasons outlined (especially not Pawn, which will generally allow you to trade the Buy for $1, twice as much).
I do recognize that this makes Market Square and Worker's Village quite a bit better. This is especially true if you want to buy a bunch of Market Squares in hopes of having one or two around for a trashing. I have certainly done that, only to find myself with a bunch of extra buys. But I would argue that that is what a lot of landscapes do. Way of the Chameleon completely transforms Poor House from a questionable afterthought to by far the most powerful terminal draw card in the game (for its price). Advance can turn a Horse or an Experiment from an cheap one-shot into Nobles or a Grand Market. Capitalism can significantly improve any number of terminal +$ cards (including Poor House again).
As for it being too weak, I think that is another common occurrence with landscapes. As powerful as Capitalism can be in some games, if the only +$ is Bard, it's an easy pass. Completely ballparking it, I would say that an Event in a game goes completely unused 40% of the time, if not more. And for some events, that happens a lot more often. Banish, Mission, Pilgrimage, Ritual...those are almost always ignored. I don't think every card needs to completely transform the game every time to have value.
I also think that it is too automatic. If I did play my 5 Grand Markets and only need 2 Buys, I will automatically buy the Event four times. It has little impact on my strategy, those 5 GMs are good independent of whether they produce 10 Coins or 12 Coins.
That's the idea. It converts extra buys into coins. The impact it has on strategy is to make buying those cards with +Buy a better proposition. As I said before, it would have little impact on the already-powerful Grand Market, but a much bigger impact on some other cards. Also, with the single copy of the State there is a little strategy in deciding whether to spend that last spare Buy and risk having that $0.5 stolen.
