In this case, if a platform existed that made it easy to connect donors with people in need, organized the transplant with reputable surgeons, provided insurance, and guaranteed the donor or their family were suitably compensated, then I imagine this would be far better than whatever black market horrors go on now.
A person should be allowed body autonomy – it’s their body, their choice. If you want to sell one of your spare organs such as a kidney, or maybe all your organs if you’re planning to euthanize, that should be your right.
Raising a family out of deep poverty will always take luck or sacrifice, there is no other way out.