You're so right,the poor will want to sell and the rich or those in need will want to buy. If legalised, then there will be no end to the illegal human trafficking that has been happening, it would increase. So many means will be invented to make it seem as though individuals gave the organs willingly, whereas, they were forced, cheated, kidnapped or killed to get it.

Do people even know how to live after selling off one of their organ (kidney)?