Big_Boy_4005 posted:Don, in addition to what the others have said about single action brushes, I really like an external mix single action. They are much easier to clean and take care of, and have no moving parts to get dirty. They can be had on eBay for $10 or less. Whatever you do, get a good air source. I use a regular compressor that can do 100 PSI, then just turn it down to 30 PSI. It's nice having a reservoir, so it isn't running every time you press the trigger.
Elliot's correct. And the perfect type of airbrushing compressor IMHO:
If you shop around, you can find a little 3 gallon oilless air compressor like this or similar to it for under $70. Try Menard's, Harbor Freight, Home Depot, etc. Quite frequently they will come with a an airline and a small handful of accessories. If so, about the only other things you might want to pick up are a water trap and extra quick-disconnect fittings.
I have a 3-gallon Husky that I bought at Home Depot about 10 years ago or so. In addition to air brushing, I also have a little air gun I use for blow-drying solvent out of train parts, dusting off the the layout, chasing off the cats, etc. etc. 
