Try the Bambi ones, available very cheaply here
http://www.aircomps.co.uk/category/p.../bambi-budget/
They're as noisy as your fridge, so you can hear the airbrush, will work happily for hours and maintain a constant pressure. Highly recommended.
Had mine since college, so about 94 I think, one service and still going strong. You can pick them up 2nd hand on ebay too. Type in silent compressor and see what comes up. However, these are cheap and I'd just get one new for the peace of mind plus it's guaranteed.