Farmer's Market triggers and self-trashes automatically. Temple provides a trade-off between having an on-play effect which is good in the early game and gaining VPs via gaining the card late in the game. Wild Hunt can gain the VPs at any time but at the cost of self-junking.
Here is another Gathering card, a simple Peddler variant which accumulates Coin tokens and self-trashes whenever you want them. It is part of a 4-6 split pile with a "resurrecter" on top of it:
Voodoo PriestessTypes: Action-Duration
Cost:
+1 Card
+1 Action
You may gain a non-Victory card from the trash, putting it into your hand. If you don't, at the start of your next turn:
+1 Buy
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While this is in play, when you trash a Demon Pirate, gain a Demon Pirate from the trash.
Demon PirateTypes: Action-Gathering
Cost: 6D
Choose one: Trash this and take the Coin tokens on the Usurer Supply pile; or
+1 Card, +1 Action, +
and add a Coin token to the Usurer Suppy pile.
Here are two (semi)-perma-durations with card-coin conversion and vice versa. As both imply a cost you can stop to play them at the cost of them ending to be perma-durations and being discarded.
Pirate HideoutTypes: Action-Duration
Cost:
At the start of your next turn(s):
You may discard a card and take a Coin token. If you do this stay in play. If you don't, discard this at the end of the turn.
WaterfallTypes: Action-Duration
Cost:
At the start of your next turn(s):
You may take
and draw a card. If you do this stay in play. If you don't, discard this at the end of the turn.
The cantrip version of
Pirate Hideout, i.e. "+1 Card, +1 Action, discard a card and take a Coin token", is to Baker what Oasis is to Peddler so it would probably cost 4$. The perma-duration version would probably be roughly balanced at 5$ (taking Lab-Hireling as rough benchmark while taking into account that a prince increase from 4 to 5 is of course not the same as from 5 to 6).
I have a harder time with
Waterfall. It is basically coins for cards which has so far only been done via Storyteller. I think that the card is on average weaker than Pirate Hideout but in some Kingdoms, e.g. in Colony games, it is pretty good.