From everything I've read kidney donation isn't that bad. As has been pointed out, most people don't have Kidney problems and having a single kidney doesn't increase your odds of having problems that much. If I could get $50k legally for donating a kidney, and if I could get a kidney for $50k in the unlikely event that something went wrong, I would certainly be willing to go through with it.

The cost paid by the buyer would undoubtably be much higher than the compensation you receive as a "donor", think about all the middlemen, doctors, nurses, etc that need to get their share. If the donor is getting $3400 the buyer is probably paying 15K at least.

Right, the cost of surgery would probably dominate the cost of receiving a kidney transplant. But that's really what health insurance is for. I guess I should have said "if other people were selling kidney's", the exact price doesn't matter very much.

Yep, on average I'd say it's a bad deal.

But if I were dirt poor in China, and I really did think that $3400 would be enough to give me the kick start to lift myself permanently out of poverty, I'd do it.

I suppose the real problem is that there's some minimum rational price for which it's sensible to sell a kidney... and a bunch of irrational people who are willing to sell their kidneys for less than that. So none of the rational people will ever get a look in, and a legalised kidney trade would only lead to misery rather than good deals.