What about a GB 400 2X10 combo? I see one for 400 in Orange county.A couple I'd look at:
Gallien Krueger MB212 combo (used maybe around $450?), 500W @ 4 ohms. Loud and light.
Genz Benz Countour combo 210 or 115 (new on closeout around $350) 300W by itself, 500W w/an extension speaker you could add later (but pretty darn loud by itself!).
P.S. If your band's PA is up to the task, maybe you can run a line from you ampeg to the PA and solve the problem for no money!!!!