Avoid the Line 6 amps, unless it's a Vetta. They are versatile, yes, but struggle to cut through in a mix. Krigloch's suggestions are good, and I would add the Peavey XXL to that list. After gigging with tube amps for a few years, I bought a used XXL head a couple years ago and have been very happy with it. It's very versatile (three channels, three "voicings" on each, 25/50/100-watt modes, three speaker dampening modes and footswitchable effects loop) and can routinely be found for around $300. If you have a little more to spend on a head, the Carvin V3M that came out earlier this year will put you into a nice tube amp and is also very versatile. It can also be rackmounted, which is a nice option.
As far as cabs are concerned, I'm assuming you don't have a speaker preference, so size should be a major consideration. The compact 4x12 cabs from Marshall and Crate are pretty poorly constructed, so I wouldn't even bother with them. If you aren't hung up on brand names, an Avatar will probably be the best value. For full-sized 4x12 cabs, the best used prices tend to be on Peavey because there are simply so many of them available. I actually like the Peavey Sheffield speakers, although some people do not.