re: Are there really people who go around harvesting organs illegally?

Not in the US.

But it's not rare in India, China, and Russia. That's according to a transplant surgeon that I worked with in residency who was from and trained in India.

He said it was usually rich people paying poor people for one of their kidneys, some bone marrow, or a piece of their liver. That or bribing Hosp admins to get the next available heart/lung.