Unless you run across a great deal on something like a Pitbull 45 or the aforementioned models, I think you might be wise to look for a good used Peavey C50 and start saving for an amp in the 1000+ range.
This might not be what you're looking for, but an incredibly good deal can be found in Pearce G2R heads, which are 200 watts and stereo, to boot. Worth checking out, at least, and I've seen them go for 300.00. Also, they can cover just about any gig situation.
Get a used 68' or 69' bassman head for about $400 or so, then send it to David Allen to have it modded. Normal channel is modded to AA-864 circuit ala Blackface Vibrolux.The bass side is modded to a Bassman Tweed/ Marshall Plexi. The mod is $179 plus shipping. You can now use an A/B box and switch between the two channels.Add multiple overdrives for more tonal options. I have a 66' Blackface bassman head with the Allen mod and I run it through a bassman repro cab loaded with Weber Californias and I can cover alot of tonal territory.