co2 or nitrogen

IMO - dry breathing air from a dive shop.
If you can't breathe it, it can asphyxiate you...had some personal experience with liquid N2 in an open outdoor environment, so I always recommend against using anything but dry breathable air for one's airbrush.

I agree with Rufus. In this day and age, you can get a really decent compressor with a tank (not a piston machine) for really cheap prices at places like Harbor Freight. I bought one there for under $50, added a moisture trap and it works great. I usually turn it on in the garage, let the tank fill, and then bring it into the area that I have my paint booth. There is usually enough air in the tank to finish whatever job I am painting. That way, you don't have to put up with the noise. I got this one (link below) at Harbor for under 50 bucks. If you sign up for their email ads they will send coupons for $$$ off.

on 9/13/2007 11:46 PM snipped-for-privacy@verizon.net said the following: NO2 (Nitrogen Dioxide) is an air pollutant, and poisonous if inhaled. Perhaps you meant plain Nitrogen (N2)

Compressors still offer the cheapest means to pump air through your airbrush. I have a very quiet Paasche compressor with tank, which I added a regulator and moisture trap.
The CO2 tank offers some advantages, but with all the hassles of getting set up and refilling these days stick with the compressor set up.

How about Nitrous Oxide (N2O)? It would certainly make painting the model a unusual experience. "Why does the Hurricane have 'Nazi' airbrushed across its wings?" "It's a traitor! It's Lord Ha-Ha's plane! 'Ha-Ha-Hawker'! Do I have to explain everything?" (Fall on floor while laughing hysterically.)
Pat

Yeah, I know its n2, and not no2--since the mind is the third thing to go (I can't remember what the first two are), that's the only excuse I can use!
Thanks for all the good input--the smaller compressor idea seems the best bang for the buck. Thanks again for all the good info.
JR