I like the potions in the item shop, but the selection is really limited. I was thinking of some that could be added at a later date:
Lactation potion: Drink it while thinking of someone and they will lactate for a short amount of time (drinking more than 2 for the same person makes it permanent) (Usable on Protagonist)
Breast Expansion Potion: Exactly as it sounds, each dose makes boobs permanently grow by 1 cup size, use on slaves in bedroom (usable on Protagonist)
Futa potion
Fertility potion
Just a few things I thought would make the game more fun.