I got too excited when I read "carbon fiber" and thought you meant the whole door, not just the panel. (black car with carbon fiber doors would be cool though)
Have you priced the aluminum? Another place you could do some price comparison is a trailer shop. They have big sheets of aluminum. And they should have different thickness' too. An 18 wheeler shop I used to work at had a trailer side and they had all kinds of aluminum goodies, a lot of mirror finished stuff too....If nothing else they could tell you where to get a deal. Just an idea.