Windmill
Action - ?
When a player announces they want to buy a Windmill, all players secretly choose 0+ cards from their hand as their bid. Bids are revealed simultaneously. The player who bid the highest Coin value discards those cards, and gains the Windmill. In the case of a tie, nobody gains the Windmill, and the active player must buy another card. If a non-active player gains the Windmill, the active player can either buy another card or try to buy the next Windmill. No player can gain more than one Windmill in the course of one player's turn.
Each of the 10 Windmill cards is unique and they are stacked as follows:
1st (top card) - gain a Silver.
2nd - gain a Silver, put it in your hand.
3rd - +1 Action; gain a Silver.
4th - +1 Action; gain a Silver and put it in your hand.
5th - gain a Gold.
6th - gain a Gold; put it in your hand.
7th - +1 Action; gain a Gold.
8th - +1 Action; gain a Gold and put it in your hand.
9th - +2 Actions; gain a Silver in hand.
10th - +2 Actions; gain a Gold.
Based on Power Grid. The idea is that normally cards are always the same so that player order won't matter, but in this case, since each card is auctioned off, everyone has the same chance to get any given card. You might announce you are buying one Windmill, hoping you will be outbid and you can then grab the next one.
(I seem to remember seeing somewhere, someone saying Windmill would be a good name for a Power Grid card, since Power Grid does have wind power)