I've considered a similar mechanic, but without prizes. It would go something like:
Name a card in the supply costing less than $8, which players will auction for. Every player reveals a card from their hand simultaneously. The player(s) who reveal the card with the highest cost trash that card and gain a copy of the named card from the supply. If the player who played the auctioneer did not win the auction, they may gain any of the trashed cards.
Of course, some of the wording isn't perfect there, and there might be other problems. But, I like the auction idea!