I haven't yet dipped my toes in the In App Purchase (IAP) waters yet, but may soon, and I am wondering one thing. Does Apple allow you to sell an IAP that gives you a semi-random item? Like a treasure chest that might give you a healing potion, or a magic crystal, or 100 pieces of gold?
I don't have an answer, but I do have feedback. I have a similar idea, and I'm thinking the same thing as you (I think) I'm surprised no one has used something similar yet, and it would be awesome!