They have so many prisoners of conscience in arbitrary detention that the supply is infinite. In terms of the way they can operate, the constraints on the system have been beds and staff, but not organ supplies. What you've seen in China since they started sourcing for organs is a building boom in transplant facilities to take advantage of this seemingly inexhaustible supply of organs.
It's true that people are treated.... They are depersonalized and treated as body parts. This is a consequence of the invective, the incitement, the hatred, against these target groups that basically leads the jailers to treat them as non-persons.