My short answer is, it is not ethical. Organ transplantation is a difficult decision all around, for the patient, and the doctor, and the donor (at least a live donor). There is great potential to do harm even when the intentions are good. Doctors are pretty serious about "do no harm", and for good reasons. I'm no expert ethicist, but since HIPAA anyone who works with confidential medical information goes through some basic ethics training. I've collected a few articles and a video that describe this in more detail, and also what happens when the intentions maybe be less than pure.
Sanjay NagralNo other field of medicine has raised so many ethical, moral, legal and social issues as has organ transplantation. Many more areas for ethical debate are likely to emerge.
At present the very term transplant is likely to conjure up an image of shady and dangerous dealings in India. If we wish to improve upon the current situation, the first step is total transparency on the part of the medical profession and open, public, debate on this and related issues. Medical professionals must set ethical guidelines and take action against violators. Representatives of the common people must be included on the committees that will oversee these operations.
We must restore organ transplantation to where it really belongs - not as an example of all that is unethical and commercial but as a modern medical advance permitting one human being to make the gift of life to another.
Here are three article which discuss some of the ethical issues involved with human organ transplantation.
The Ethics of Organ Donation by Living Donors
Ethics of Organ Transplants (Why this is listed under agnosticism and atheism I do not know).
Ethics of organ transplantation, an except of which is quoted above.
Finally, here is an example of everything that transplantation should not be: A negotiable commodity available to wealthy criminals.
The rules for organ transplantation are restrictive because they need to be. I do understand the appeal of the "open market" option that my friend likes, but it opens the door to many evils as well.