I use the Ashton BSK158-
http://www.ashtonmusic.com/productView.asp?productID=65
It cost me £120 brand new.
It's a little beast I charge it up over night and it lasts 6 hours, I get 3 hours of proper volume after that it fades a bit. I use one channel for my vocals and the other for electric guitar.

I'm saving up for a Roland for my vocals-
http://www.reddogmusic.co.uk/Guitars-Amps-and-Effects/Guitar-Amps/Guitar-Combos/Roland-Cube-Street-Red.html?origin=googlebase

Its more expensive than the Ashton at £199 but I've heard many of these amps in action and they are loud and the sound quality is very good.