I don't have a ton of dough to spend, but the frame doesn't have to be the latest or greatest, just functional and not too porky. I've got about $300 to spend (could add to that total through parts such as XT shifter, XTR rapid rise rear derailleur etc. etc.)

Maybe you've got an old school Heckler laying around, or an older Enduro or something along those lines. If so, send me a PM.