it can be a good idea but has a big problem, and that is the issue of trusting you.
since you are the one creating the paper wallets and the private keys, the buyer needs to trust you are don't have the the private keys so the paper wallet won't go empty after the purchase.
if the amount of BTC (purchased in this way) is relatively low then people could trust based on positive feedback from other clients. But you definitely need to proof to big volume buyers that the paper wallet won't go empty after the purchase.