Out of curiosity, does your "NAPA" double action air-brush work at all? If it does work, you might consider sticking with it in the near term. Since you're still really learning to use the airbrush, you might as well learn on the one you have. Once you've more or less mastered it, if you want to change, you would have the experience to better evaluate the pros and cons of the various airbrush alternatives that will be suggested.
On the other hand, if it does not work well, or just simply want to be treated on your anniversary (I wish you a happy one at that), I would recommend against Aztek. I had one, followed all the cleaning and general care instructions that came with it, and it died after a short service life. I've heard from a number of other people who shared the same experience. The Badger 100 usually is well recommended. Although I own a Badger 200, which is single action, it is a very well made device, and would infer from it, that the good things that I've heard about the Badger 100 are to be believed.