modelbuilder - do a search for "airbrush suggestions" or "good airbrush" and you will see a lot of posts on this. There's a lot of them out there and there will be a lot of different opinions on which is the best. My vote is on a double action gravity fed model. The Badger 100LG with a medium tip and needle, Badger 360, the Omni 4000, The IWata HP-CR and Iwata HP-CS are all very good examples of these. Try looking through www.dixieart.com and seeing what is out there and ask about certain airbrushes. I am sure several people will have the one you ask about and be happy to give you some good remarks on it!
Also you can check out this site for some more good advice and clarification on some of the terms you'll hear used (single/double action, internal/external mix etc...) http://www.craigcentral.com/models/ab.asp