This is really good, and I strongly encourage you to consider pursuing it commercially !
To help you out, here are a few suggestions :
- The mouse could be replaced with the keyboard to make the gameplay smoother.
- 20000 pieces is way too much, especially considering there aren't that many buyers.
- Perhaps you could consider adding special potions that are worth more or allowing players to combine a pre-made potion with ingredients to create enhanced potions.
- Also, I would have preferred less time spent on back-and-forth movements and more on potion creation, but those are just personal preferences.
I think that's all I can see for this prototype to get better...
Feel free to try out my game as well, this game jam has also inspired me to consider commercial ventures, and I'd appreciate any advice you might have towards that goal.
PS : However, I don't really find that it fits the theme "On/Off" all that much...