It would be nice if you could add in some extra ingredients without too much punishment as long as you still follow the required rules. Such as: +$ for perfect match. Nothing for wasting ingredients. Bigger -$ if you give something you shouldn't (Ex: butt potion vs skeleton).
Could also have some adventurers start asking "Where can I find ____ effect?" and then directly sell them that effect for bonus/story? Your shop keeper could claim they figured out how the dungeon traps give their effects and are selling them.
Good luck with your game.