Potion/Poor House: 65.66%
Potion/Lighthouse (or Fishing Village): 65.78%
Potion/Oasis (I'm only about 90% I calculated this right): 71.97%
Potion/Moat (or Shanty Town, any draw 2): 77.02%
Potion/Great Hall (Trashing Hovel): 83.33%
The key insight here is that not drawing your potion is actually MORE important than the nightmare of 2+p. So cycling goes a long ways - which is good, because that also synergizes with what you want to do with the potion-costing cards anyway, whether at 2p or 3p. This changes, of course, once you start needing 4p, though the potentially bigger issue there is that you don't really want Golem before you have actions to go with it.