willys is right, these guns are really getting affordable. you don't have to spend a lot money but make sure that your gun is really adjustable so you can fine-tune your spray, ie. air in, paint volume, pattern nozzle, etc.
psi is usually around 35-40psi going into the gun with about 7-9 coming out the nozzle. don't forget to use a watertrap filter.
"Well done is better than well said." - Benjamin Franklin (1706-1790)