Supply Variations is interesting, gold rush seems a bit strong but is possibly okay,
Note that Gold Rush gives your opponents a turn to buy Gold at the reduced price as well.
don't like shortage because of the lock out of game potential (pirate ship/theif away their treasure and kill the coppers).
Yeah, that's fair. It shouldn't be able to target Copper.
Boom Town seems pretty bad without actions giving money and maybe too good with the right actions, especially with minion.
I think you're probably right. It just mainly seemed super-thematic.
Paper Currency just seems mean, because odds are the person who's ahead buys it, and then everyone has a hard type buying Paper Currency.
I think you're probably right about this as well. I was basically trying to figure out a way to have a deal where you vary what basic Treasures are in play while maintaining the present framework of the game. It may not be successful.
Maybe a better or more interesting variant would be:
Paper Currency$4 - Treasure/Victory
$2, 1 VP
If anyone gains a copy of this card, put a Forbidden token on the Silver supply pile. A supply pile with a Forbidden token on it may not be bought from.
Since it's a lot less painful to try to reach $4 instead of $3, than $7 instead of $6. The main problem there is finding something that's "a little better than Silver."
I just think that it would be interesting to have to adapt to a game in which Silver and Gold aren't always there in their normal forms. Probably overall extremely difficult to balance, though.