How about a karate monkey complete? I don't think you need ALL of the versatility of a troll/ogre..this seems like a decent compromise.

Or if that's still outside the price range you can try:
KM frame + fork.=$450
Bike island donor bike http://bikeisland.com/cgi-bin/BKTK_S...ls&ProdID=2443
The 19" one is no frame for parts only at $250 off.. = $250

Pay a LBS to put it together = $150-$200..

I'd just buy a complete but this may be cheaper..

You could also try and build it up yourself..and only go in for the frame prep + headset installation..there are coops + people who would be willing to help you do it and loan you the tools. Plus, it would help you become slightly more mechanically inclined.