The Economics of the Baby Shortage
The Regulation of the Market in Adoptions
Other authors have written on the subject as well:
The Free Market Approach to Adoption: The Value of a Baby
A Modest Proposal to Deregulation Infant Adoptions
For those of you coming into the thread now, I'm not promoting the selling of babies. I mentioned earlier that Posner is primarily an economist who has writes about economic maximization - economics and the legal system in a morally neutral setting.
Thanks for the links.