[font=trebuchet ms]Lurk on eBay. A late-60's-to-early-70's Traynor YBA-1 Bassmaster head can be had for ~$300. A Magnavox-era Ampeg V-2 head may run a bit more - say ~$400. A used 2x12" or 4x12" cab shouldn't cost more than $300.

That gives you a rig you can do amazing things with for as long as you want to play. And you've still got some coin left for a couple of pedals.[/font]