I got mine, similar to the one FumbleFingers has for about $70.00 at Lowes... another $12 for a moisture trap and you're done!!! later you can change out the gauge for one that has smaller increments ($24 at Hobby Lobby) but it will work MUCH b etter than spray cans and equally as good as the higher end compressors.. just noisier... it's about as noisy as vacuuming the floor maybe less, but it only comes on every so often just long enough to top off the tank... it's not continous.
What I am about to do is get some fiberglass AC plenum insulation (it looks like drywall) and put it inside the walls of a box and enclose the compressor. A friend of mine just did it and says you can't really hear it from across the room even...
Most AC places will have scrap stuff for cheap or free if you wanna try it later...
---edit---
the one Mike posted is not much more expensive, and is definitely quieter, so if noise IS an isse then I would look to that one... if not the hardware store type works fine...