What's wrong with selling organs?

I have always wondered why the private sector hasn't put up kiosks to accept donated organs. I imagine something similar to a pawn shop where people go, have some organ removed or maybe sell it for a later removal date, and then receive some type of compensation for their organ donation. Some sceptics out there claim that this would lead to some type of "organ harvesting", where people are killed for their organs. It is true that people steal merchandise, such as jewelry and electronics, to pawn, but I believe killing someone for their organs is a little different. First, there is no way a person would not get caught organ harvesting. Second, there would have to be some type of log or other way of keeping track of who donated what organ. The organs would have to be donated at the site or kiosk, not brought to the kiosk in a cooler. The argument pawning organs leads to murder is like saying undertakers should kill so that they receive more business. It just doesn't make sense.