How many organs can a living person simply give away? 1 kidney, and part of their liver?
Can't donate a heart or lungs without the person being deceased.
People can donate either one right now and some do freely to save a friend or a stranger.
Fair point that this probably really only applies to kidneys and blood/marrow. If they are allowed to donate, why shouldn't they be allowed to sell? Looking for actual rationale. I cannot come up with one that does not invoke paternalism/nanny state/"I know what is good for you even if you do not" line of thinking.