I know your question pertained specifically to air-tools, but I just wanted to throw two-cents in on body tools...
Don't go cheap on hammers/dollys. I know that you can buy the cheapy kits for around $25.00 that include multiple hammers and dolly's, but these are junk. You can absolutely tell the difference when you pickup a $25.00 martin dolly.
Air-Tool wise, I only have two pnuematic tools...a cut-off wheel and a DA-Sander. I bought generico-brand, and they seem to be holding up fairly well to the work I've put them through.