I think that if the regulated price was either a ceiling that is low enough, or a floor which is high enough (or both, as in the case for wages), then harms would not result at all. A law which said "all organ selling must be either a free donation, or accompanied by a payment of at least $2 million" would probably be okay.
But that is a very noncentral description of organ selling. The majority of advocates of organ selling don't want such limits on it.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.