I think this could really be a field that would "take off" if certain technological advances were made. Yes, I know there was a pun, there, but seriously...
Aerospace Medicine has traditionally been a military field, and when you do a FREIDA search, you'll find that there's only one "Civilian" program (UTMB at Galveston).
I think they study the effects of air and space flight on the human body, and they work with NASA and stuff. Working for the government has never really been a way of making tremendous amounts of money, but I'm not sure about those figures so I can't say with any certainty. That said, Galveston has a combined program with Internal Medicine, so it would be a nice program to get into. The only downside is the amount of spots: 2 each year (I think--I'm doing this from memory).
Anyway, it's exciting. This link may provide you some insight:
<a href="http://www.studentdoctor.net/guide/medstudent/specialties/aerospace.html" target="_blank">http://www.studentdoctor.net/guide/medstudent/specialties/aerospace.html</a>