Do you have a cab already?
Or are you looking for a combo where it's an amp and speaker?
If your looking just for an amp, check out Gallien Krueger MB200.
It's my favorite practice amp right now. You can use headphones or a speaker cab of your choice. They are $300 new or $200 used.
It's very simple amp that puts out 200watts and weighs 2lbs.
If your looking for a combo, there is plenty in the classifieds of TalkBass and Craigslist.
GK Club Member #996
GK + Ampeg Club Member #6
Eden Club Member #310