The best Peddler comparison is actual Peddler.
PeddlerNormal price:
Semi discount: requires 3 actions in play, can buy as many as you have buys for
each
Maximum discount: requires 4 actions in play, can buy as many as you have buys for no
FishermanNormal price:
Semi discount: requires empty discard pile, can only buy one for
Maximum discount: requires empty discard plus a topdecker, price is still
each