I just finished my first AC compressor build. It works great. Now if it just lasts. The cost for switch, fittings and tubing was about $100.00. I got the switch and check valve from Graybar and the rest of the parts from Lowe's. It didn't turn out to bad. The compressor is from a 5000 btu window unit. It pumps up to 80 psi then kicks on when it gets down to 60 psi and it will keep up with the Paasche airbrush. So far so good. Oh, the tank came from a TC 20T unit that broke the motor shaft. The unit I built puts out more air than the TC 20T. I wish it had a bigger tank, but then it would be less portable. It works fine as is. Gio Urbani was a big help with information on hooking it up.