This is by no means I final product, I've just been fiddling around with this concept and I was wondering what you guys thought:
[4$ Action]
+1 Buy
While this card is in play, when you buy a card, gain a silver, putting it at the bottom of your deck.
The mechanic is ideally meant to work sort of like stash: Play enough of these in one shuffle, and you can accumulate enough silvers at the bottom of your deck and ensure you draw a hand with 4 silvers, thus giving you a province. I'm just wondering about what else the card should have. I think the + Buy is a necessary part of it, because it adds the decision sometimes of whether or not you want to actually use two buys (thus getting you another silver), or use only one, or use one buy to get a good card and also buy a copper, so that you get another silver. (If you have 3 at the bottom of your deck already, for example, getting a 4th one could help ensure you get a province)
So...what do you guys think? I'd love to hear any other ideas about how this mechanic could be implemented, or what other effects the card could have to make it more interesting.