I third (or is it 4th, I'm far too lazy to count) the Screamer.
Some other options are the Laney GH50L, it's only a single channel amp, but has switchable gain. If you really need a different clean sound you could always throw in an EQ pedal, and perhaps a chorus.
Ashdown Fallen Angel is in your price range, but I'd definetly try it out before making a leap and buying it, theres alot of mixed opinions on this amp.
Peavey XXX could be what your looking for. I haven;t tried one out for a long time and am not totally sure on the price, but could be something else to look out for.