A few years ago I went looking for a used XR. I found a xr400 that had some extras, and the guy had it at a reasonable price. I was able to ride it, sounded good. It needed some cosmetic help, but not much. When I asked about a title, that's when the stories started to fly. My caution meter went through the roof, and I told him I'd have to think about it.
I called my DMV with the VIN, and I was told there was some type of lien on the title. Needless to say I passed.
My advise is check the VIN through whatever means you have available. If it doesn't run, and you (or someone you know) aren't ready for what could be a total overhaul of the machine - pass. There have been times in the past my voice of reason hasn't been loud enough, and I got into something I regretted.
Also, if your looking at a used BMW in your area, go to the marketplace/flea market sections of
www.ibmwr.org or
www.bmwmoa.org , and you can usually find the same model to see if that is close to the going rate. In any rate you might find something in better condition, better situation, and at a fair price.