An airbrush is a tool, nothing more, nothing less. Get a good one, learn to use it properly, and never look back. Get a Badger, Iwata, or Paasche and you'll not be sorry.
I don't want plastic tools, and I don't want a plastic airbrush. I realize a lot of people like the Aztek, and since I have never personally owned one I can't speak from firsthand knowledge, however the vast bulk of the posts regarding them on this forum are not positive. 90% of the abilities of an airbrush are in the hand that holds it, but the tool has to work properly to be effective. Go to the painting forum and search the posts for the word "Aztek" and you'll see what I mean. To the guys that use and enjoy them, I think that's great and I'm glad they are working for you.
Edit ... I forgot to mention that I think Digger's idea of a check list is a great one. Find out what is availably locally and think long and hard about them. Needles and nozzles never break until you absolutely positively have to paint. Having a local source for parts is a big plus.
I recommend a double-action airbrush because of the flexibility. They are slightly more difficult to learn to use initially, but the flexibility is worth the effort.