As a general proposition it seems reasonable that the individual has autonomy over what happens to their own body and that everyone has an equal right to life.  To protect this right, many societies feel there is an obligation to ensure that every person -- whether rich or poor -- has equal access to the benefits of medical care.  But if a market in organs or other body parts were to develop, ability to pay would determine who could buy organs, while economic need would determine who would be motivated to sell their organs. The very wealthy would end up buyers of the organs being sold by the very poor. A market in organs would thus benefit the wealthy while putting pressures on the poor to endanger their own health. Whilst some would consider this is just the ‘free market’ in action I am not convinced this is just nor something the medical profession should endorse.

Allowing organs or body parts to be bought and sold would lead to what some call the "plundering of peasants' parts for profits, essentially the exploitation of the poor and desperate, especially in impoverished countries. This is already occurring with women from India ‘renting out’ their womb for couples who want children but cannot. There are  examples of some women having 7 or 8  pregnancies with the  inherent problems and risks it places on the surrogate women. Whilst they receive financial recompense for being a surrogate, at present such practices are unregulated and the amount paid is substantial to the surrogate, however  in  UK terms the amount paid is very small. Such a scheme would encourage the most vulnerable in society to treat themselves as commodities and allow others to violate their rights for commercial gain.

These thoughts above deal with just one narrow field but I tend to think that selling organs or body parts in any commercial way is fraught with ethical problems. Having said all of that I believe it perfectly possible in time that some sort of selling process of organs/body parts may emerge but in a limited context. Speaking purely in terms of organ donation (i.e Kidneys etc) where organs are desperately  in need and thousands of people die because they cannot undergo transplantation we will have to choose between different sets of moral values: the value we place on preventing death and alleviating suffering, and the value we place on respect for human dignity, and autonomy and our commitment to meeting human needs in a fair and equitable manner.