Lisa,
Depending of if you want airbrush for nails/ tanning/body art will depend what you get. Nozzle size determines what the airbrush is for (usu .2mm for nails, .4mm for body art). The airbrush is just the bit that holds the paint and sprays it onto the nail. A double action airbrush is best as it allows you to control air and paint flow with one trigger.
You will also need a compressor, this provides the air that is sprayed through the airbrush with the paint. This is usually the more expensive bit. Required usage usually determines the size/ weight/cost of the compressor (it's no good buying a little mobile one if you intend to run it constantly in a salon). The compressor should have an air regulator so you can adjust the pressure (e.g. 20-25psi for nail art, 15-25 for body art), a moisture trap (so water is collected separately and doesn't unexpectedly spray out from the airbrush ruining your design).
A good kit should also come with paints, stencils, airbrush cleaner (and warranty if new). The paints must be the correct ones for the job (water based acrylic paint specifically for airbrush use for nails) - if the paint is too thick it will clog the airbrush.
It's also worth investing in at least 1 days training, so you can learn how the airbursh works, how to look after it (most important - easy to clog if not thoroughly cleaned), techniques for spraying etc.
For more info check out
www.allthingsnails.com - email the site owner Melle with any questions you have, anything she doesn't know about airbrushing isn't worth knowing! Melles training is also excellent - worth investigating.
Also try K-Sa-Ra (
www.netnails.com I think) - Rachel Myatt there is also ace airbrusher, lots of geeks have done their training with her and highly rate it.
www.airbrushes.com website for The Airbrush Company for loads of airbrushes/ compressors / kits and accessories. For other IWATA stuff email
[email protected] who also supplies airbushes (got my Iwata kit complete kit from him, same as from the airbrush co but cheaper and he's very helpful and will also answer questions).
Hope this helps, or at least gives you somewher to start!