Beyond the issue of creating human beings in order to kill them...
Does anyone not see the danger in selling human body parts for money?
In the United States, you can't sell yourself into slavery.
It seems to me that selling body parts is paving the way for a return to slavery.
It seems obvious to me that if you can sell part of a human being, you can sell all of him (or in this case her!).
And it's a short distance between voluntary slavery and involuntary.
Our concept of personal autonomy cannot be divorced from the dignity of the human person. You can't use your autonomy to degrade yourself, at least not in the public realm of "the market".