Well, it depends on what you plan on using it for. Are you going to try to paint model kits and weather props with it or are you going to use it to touch up your car?
Personally, I've been through the cheap brushes and I refuse to buy anything but Iwata ever again. But then again, I use mine for fine detail work on 1/6th scale model kits, etc. So, it depends on what you want to do with it and how often you plan on using it. Is it a one shot deal? Are you just going to buy it for one project and never touch it again, or is it a tool you see yourself using often?
Also, on the subject of air supplies for it, don't get sucked into the canned air crap. By the time you buy ten cans of air you could have bought a decent compressor. Or if you live and work with this airbrush in an area where you need to be quiet, get a CO2 tank instead. They're moisture free and silent, so no neighbors complain about the noise of the compressor.
There are a lot of good deals at Harbor Freight for cheap tools, but with airbrushes you usually get exactly what you pay for. Considering that it's only $5-$10 though, it's worth trying it out. Otherwise, I'd recommend BearAir or Dixie's Art Supply for great deals on Iwata brushes, if you want a brush that will basically become an extention of your arm and last you a lifetime of painting. I'd suggest an Eclipse, which I've never used, but I have had friends rave about it, but my personal brushes are both HPCs. You can almost sign a check with it if you're careful. Or you can get the top of the line detail brush and go for a Micron....I'm still drooling over it, but even at half price through Dixie's it's still $265 and it's their most expensive detail brush. PM me if you want to talk about it more.
Hope this helps
Raygun