Had I the funds, I would pay them for their gift, not becuase they should be paid, but as a small token of gratitude. I would hope they used the money for other selfless acts. Or for much needed help with whatever unfortunate situation they might be in today.
Should people be able to sell their own body parts? I say Yes, if it's an informed choice, and no life is threatened.
Shifting gears slightly....
Any elected official who just keeps complaining about Roe v Wade without taking action to overturn the case is wholly unqualified to serve in office, because he or she does not understand how laws work in this country. They need to draft legislation and see it enacted. Overturning Roe will require a State to enact legislation banning abortion. That law will make it's way to the Supreme Court, and the Court will render it's decision.
While Roe may have set a precedent, it was only binding on the parties to the case. States are still able to enact new laws on their own (see Amendment X), regardless of what SCOTUS says about prior laws. As personnel change on the court, so does the court's opinion change with time.
Society has decided that money can unduly influence people, and that body parts are too important to allow people to have to sell them for money.
There is a selfish motivation as well, since a lot of people donate organs but if you could sell them NOBODY would donate them. We should be allowed to sell blood, but you can’t because it would drive costs up for blood transfusions.
You CAN sell platelets though.