Trinin
Territorial Art
Well, first you need something light and not too big.Maybe you can get a yamaha half stack?I heard those work pretty well for gigging.. A tad too loud and tend to sound wierd if you're just gigging. I'd suggest a Fender FM 212R combo amp. IT's pretty light to make it easy to move around a stage or whatever. But it has great sound and great control. I know it's under $400.
Most of the peavey line just under 400$ is pretty fair to use, but you can't go wrong with the Fender 212. If you want to model tones you can get some pedals to go with it; you can make your rig sound like anything you want then.