Why do you suppose doctors are so desperate to get these organs? It wouldn't have anything to do with the enormous shortage of organs currently available would it? A shortage that would ease significantly if people were allowed to sell their kidneys, significantly increasing the supply.
Your world view seems to be very brutal and dog eat dog.
I'm a realist. Life must be pretty hard over there if people are willing to sell their organs, but until that changes do you really want to deprive them of one thing that could significantly a few people's financial position? Or should we ban it to protect their dignity (while they continue to live in squalor)?