You cannot sell your organs. You can be a registered donor and take a donation for them in America. Other western places you often have to be a relative. Everybody is a registered donor on death in most of the World, you have opt out to prevent your organs being removed. Almost 90 percent of organs removed aren't transplanted. The majority are simply dissected or become medical waste. Organs are removed regardless in most cases of autopsy. You own nothing especially if you are poor. Or work for uncle Sam. Army police and civil servants it is harder to opt out.

Like almost everywhere there is the black market. It happens in the West. Where it gets dark. But in the 3rd world. Where life is cheap. Brazil, Mexico, Cuba. Etc. Egypt. India. Africa. Indonesia. Plenty of places globally if you trust their procedures. Where you can buy almost anything avoiding donor waiting lists. Today some of these operations are irrelevant with stem cells grown from fetuses, pigs, and monkeys sometimes even 3d printed into organs. Removing the need for donors.

As far as Chinese cannibals. They exist.

In this topic they literally do anything to their citizens.