Radley Balko yesterday, in a post responding to a juvenile bit of organ-based libertarian-baiting from the Village Voice's Roy Edroso, briefly rebutted the argument that giving people the right to sell their own organs would lead to exploitation of the poor. Today, over at the Volokh Conspiracy, Ilya Somin, who teaches on the subject at George Mason University, gives a more detailed, four-point case against that one objection. Whole thing worth a read.
I'd add one point infrequently made during these debates: As Kerry Howley demonstrated in a classic, award-winning March 2007 Reason article, the buying and selling of body parts in the United States is a widespread, profitable phenomenon. In the words of her subhed: "Everyone's making money in the market for body tissue -- except the donors."