Just had an email from The Airbrush Company announcing the new Sparmax battery powered airbrush compressor that can either run off whatever mains power is available (it's a DC motor), or work off a battery pack that can be recharged, with spares available for the really intrepid modeller!
There are going to be a number of package deals on release, but this is the top of the line one. Not cheap, but if you want to be able to airbrush anywhere, it's got to be up for consideration!
More news when we have it, and we'll try to get a sample to see if it's suitable for all you road warrior modellers!