onboard air compressor?

[GreenMystChevy]

I posted this in the 67-72 message forum but someone suggested I post here also.

I'm building up my 4x4 and would like to put air on it for a few reasons. I want to install an air horn and I would also like to be able to air up whenever and use an impact gun on the road. The problem is that I don't want to spend the cash that 4x4 places want for these shiny new things.

Does anyone know what or where I can get something that I can wire up under the bed to fill a 5 or 10 gallon air tank that will do the trick? I am not looking for something that outperforms all others, just something that will do the job.

Even though a belt driven one would be pretty slick, I'm not too fond of putting something else under the hood that I have to mess with. I'd just rather it be somewhere where I can hook up some wires and plumb a tank with a pressure shut-off valve.

I know nothing about compressors so any help would be appreciated. Anything that I should stay away from, what is way too small and too big, what kind of things to beware of, etc...