Ilya Somin enters the fray here with some worries about legalizing voting markets, as well as some further criticism of the anti-commodification theorists. An excerpt:

For example, many people oppose legalizing organ markets because they believe it would lead to exploitation of the poor. But most of them have no objection to letting poor people perform much more dangerous work, such as becoming lumberjacks or NFL players. If it is wrong to allow poor people to assume the risk of selling a kidney for money, surely it is even more wrong to allow them to take much greater risks in order to increase their income.

If you believe that organ markets must be banned because they exploit the poor, you must also argue that the poor should be forbidden to take jobs as lumberjacks and football players. If you believe that such considerations justify banning participation in organ markets even by the non-poor, than we must also categorically forbid monetary compensation for football players. Indeed, the case for banning the payment of football players is actually much stronger than that for banning organ markets. Unlike the ban on organ markets, a ban on professional football  would not  lead to the deaths of thousands of innocent people. 

Other critics believe that organ markets must be banned because it is inherently wrong to “commodify” the human body. Yet most of them have no objection to letting a wide range of people profit from organ transplants, including doctors, insurance companies, hospital administrators, medical equipment suppliers, and so on. All of these people get paid (often handsomely) for helping transfer organs from one body to another.

Perversely, the only participant in the process forbidden to profit from the “commodification” of organs is the one who provided the organ in the first place.

Also, Benjamin Barber writes a response to my response here. In his response, his disavows the fields of political philosophy and political theory in favor of partisan, in-the-dirt politics.