I come out with a few ideas (without names) using this wonderful ideas that are Coin tokens :
-Card 1-
Action, cost $3
Set aside 2 Coin tokens. At the start of your next turn, take them.
Please note that it is no duration card, so you can play it every turn, and hey duration cards give you a bonus only on that turn and the next one ? Here, you instead sacrifice an action a turn in order to gain a more flexible benefit, and if you manage to play several of them, or TR-KC-Procession them, why not...
-Card 2-
Victory, cost $6
Worth 2 VP --- When you gain this, take 2 Coin tokens.
So you buy it, and you can spend another extra $2, this turn or later if you missed the province. I think it should be right at 6, like Farmland and Harem which are worth the same amount of VP.
-Card 3-
Action attack, cost $4
+1 action, gain 1 Coin token. Each other player with more Coin tokens than you chooses one : he discards down to 3 cards in hand, or he returns one Coin token to the supply.
This one leaves me with a doubt : at least it's a non-terminal CT-gainer, but it can lead to boring games as you can't choose to save your CTs for later without being targeted by the attacks ! But on the other hand this concept of "card that attacks player with more CTs than you" seems fun to me. So what ?
Then, what about a card that also gives you Coin Token on reaction (for example when an opponent plays an attack card, or when you discard this outside of Clean-up phase like Tunnel, or... ) ?