If the sale of human organs becomes legal, a black market will spring up immediately. There are people who will be more than happy to murder others to get access to their organs, either for themselves or to sell on the open market. The extreme protections surrounding the harvesting and transfer of human organs are a good idea and should remain in place.
Human organs should not be a for profit business. They should remain available to patients who need them on a donation basis. Promoting the sale of organs creates a black market in which people's organs are involuntarily harvested. Furthermore, people with extreme financial need may be convinced to sell their organs without fully comprehending the long-term health effects.
People are always in need of organs for replacement and improvement. There is a long list of recipients waiting to receive a vital tissue that they cannot live without. Creating a secondary market that expedites the process and allows for speedier delivery to those who need organs most is best with secondary markets that function on capital rather than insurance.
Many people are in need of an extra kidney, a replacement liver, and the like due to various health problems; many are on waiting lists and die before they have the opportunity to get a new organ. If people were willing to sell organs, then it might save the lives of some people who would otherwise die because donors were not available.