John - I use a $65.00 compressor from Lowe's with a 2 gal tank and it works fine for me. It's not terribly noisy, once you've used it for a bit you don't even notice when it turns on to fill the tank. My wife says it doesn't bother her either, my modeling cave is at the back of the house and usually she is in one of the living areas so I don't think the sound carries much. For the money I spent it has more than payed for itself.
It probably won't come with a regulator when you get it so you'll need that and a watertrap, but as you already have a compressor I am sure you can use the ones off your old compressor. If the regulator is made into the compressor you can go one of two ways, either buy the commerical style regulator fromt he hardware store along with a moisture trap, or order one from www.dixieart.com or somewhere like that. A lot of the ones on thier site will come as one usnit with the moisture trap interated into the regulator.
Good luck!