The Boston Globe's Jeff Jacoby eloquently challenges the refusal to allow transplantable body organs to be freely bought and sold . Here are his closing paragraphs:
No one would dream of suggesting
that medical care is too vital or sacred to be treated as a commodity,
or to be bought and sold like any other service. If the law prohibited
any “valuable consideration’’ for healing the sick, the result would be
far fewer doctors and far more sickness and death.
The result of our misguided altruism-only organ donation system is much the same: too few organs and too much death. More than 100,000 Americans 
are currently on the national organ waiting list. Last year, 28,000
transplants were performed, but 49,000 new patients were added to the
queue. As the list grows longer, the wait grows deadlier, and the
shortage of available organs grows more acute. Last year, 6,600 people
died while awaiting the kidney 
or liver or heart that could have kept them alive. Another 18 people
will die today. And another 18 tomorrow. And another 18 every day,
until Congress fixes the law that causes so many valuable organs to be
wasted, and so many lives to be needlessly lost.
Update: Jeff reminds me that he first wrote about this topic back in October 2003 .