One alternative is the approach where the buyer side is not punished or at most fined for its activities (as long as it doesn't harm others), but the seller side is strictly regulated or even illegal.

It's sort of right in between letting people free to do as they please, and guiding them in a certain direction or curbing excess.

It's how Holland deals with weed and ecstacy, for example, and for the most part it seems to work. That said, personally I think I'd prefer proper legalization with heavy regulation if necessary.