testors aztek airbrushes are about as worthless as airbrushes come. badgers are okay for student grade. for the best and most painless airbrush experience, nothing beats an iwata. it may be expensive to start with, but it will pay for itself in the long run.
badgers break down often because they use a lot of bad parts. cheap plastic, brass, etc. will slow down the performance of any airbrush.
iwatas are almost 100% stainless steel except for the o-rings and washers. they are also backed by an excellent warranty and customer service.
i'm sorry to say but that aztek is really not worth half its retail price. i can't think of a single professional who uses it for anything more than a doorstop.