I've got a 10lb air tank set-up and it works really slick. I fill it up to 125 psi at the gas station and I can get through a Hase VF-1 (base coat, clear coat, clear coat and dull-coat) without having to refill. I prime with the a Tamiya rattle can and spray at 15 psi. The nice thing is its cheap, silent and compatible with a compressor if I choose to upgrade in the future.
Its probably not as convenient as a regular air-compressor, but its definately better and cheaper than using cans of compressed air.