I use the Wimzy Creations Airbrush Pro Kit and I love it. Its portable and easy to control. Ive been recommending it to all my cake decorator friends. and so far everyone who's tried it loves it. I got it from cakes supplies 4 u for a really good price. plus they have a one year warranty, case anything happens. (:
I just received this one on Sunday:
I am extremely happy to get it at very cheap price. You can try it may helpful for you.
Just my two cents...
I have this compressor (whatever compressor you buy, make sure the air is adjustable)
and this airbrush:
I don't do a whole lot of detail with the airbrush so I can't speak for that, but it works great the basics that I use it for (I'm sure it would do well with more if I took the time to learn).