Ah I don't come into Kopitiam often, 2nd time ventured in here.
I can tell you that donor families don't get charged for anything related to organ donation, lab tests, extra stay, the donation operation itself. And 99.9% of the time, there's a mechanism to waive off the entire bill for organ donors, out of goodwill for the kind act.
As for China's executed prisoners' organs and also other countries associated with paid organ donations, India, Pakistan, etc: yup they exist but their relevant authorities are trying their darndest best to clean up the act. With high demand, I'm not sure if it'll ever be eradicated. Saddens me to say this but there are always middlemen waiting to make a good profit, and many more poor countries to whom they can prey upon.