I started with a cheap Testor Aztek airbrush and hated it. It spat and sputtered all over my cakes. I then upgraded to a mid-range brush, the Badger (the iwata is similar) and really enjoyed it. After another couple of years I finally took the plunge and spent big money on a Grexx. It is the best airbrush I have used, although I can see not wanting to spend that much on it unless you really know you’re going to get good use out of it.
Not sure if you have any place near you where you can try them first, but that makes all the difference.
Jenniffer White, Cup a Dee Cakes - http://cupadeecakes.blogspot.com