What does that scenario look like in practice?

Suppose I'm the evil coercing person. I have an artificial kidney and $X, you have (still in your body) a real kidney, and you're short of money so you prefer (artificial kidney + $X) to (real kidney). We make the trade.

Why would I do that? Presumably so that I can (evilly) treat someone with kidney disease by giving them a real kidney, which they prefer to an artificial one. In fact, to make it worth my while they must also be paying me at least $X more for the real kidney than they would have for the artificial one.

So the incentives work out provided my patient prefers (real kidney) to (artificial kidney + $X), and my victim prefers (artificial kidney + $X) to (real kidney), and what I'm doing is (evilly, coercively) enabling them both to get what they prefer.

It's hard to see how I can be doing anyone very much harm here. Presumably the idea is that the victim is worse off, having been persuaded to give up their precious real kidney for an inferior artificial kidney in exchange for mere money, but also-presumably they are poor enough not to have the luxury to use phrases like "mere money" and $X is a life-changing amount for them. Which probably means their situation at the outset is very bad, but that isn't my fault.

I expect there are possible situations where the existence of artificial kidneys enables some things to happen that look good to all participants but end up being bad ideas in the long run. But it seems super-implausible to me that these could outweigh the benefits of being able to make functioning artificial kidneys.

So an “organic organ” market? Cruelty free? No artificial?

Possibly, but if artificial kidneys (or artiforg) becomes viable for all types of patients. It would make sense to ban live organ transplant. Anybody caught transplanting live organs without a valid reason and reasoning signed off in triplicate will get their license revoked and jailed for many years. Co-conspirators to be jailed as well. Supermax, no pass go.

Of course something like this only works if the international community is synced. Nothing to stop a group of (rich) people from flying to a country without these laws and organ shopping.

Why would that be desirable, though? The artificial kidney would likely be superior just because it doesn't require immune-suppressant drugs. I don't think there'd be much of a market for that sketchily-obtained real kidney.

If this doesn't get rejected by the patient, how would that even make economic sense?

I saw that movie too. I think is based on a book though.

I doubt it as the artificial one will probably be very expensive.