The money sounds right. Still want to check all the obvious things if you can, compression etc. I think that's a twin shock model. Either way, yeah it's a cool bike, but it's not an XR100, smaller wheels, 16" front 14" rear I believe, VS 19" and 16" on the XR100. Probably about 6 horses instead of 8 for the 100. You can still get it around Aaron's track, just don't try to do what he does. It'll end in tears.
If it's an unmolested bike it's definitly worth it.
FR