That's a steal! I agree, if you can't get it working, you could always part it out for that price, worst case.
But for that price, whatever you need to put into it to get it working and/or perfect will be worth it. You've got about $1500 to spend on it to get it working nice before you'd hit anything close to a ceiling on what you could resell a nice, decent looking working bike for.
And that's if you never actually rode it and got any of your investment via enjoyment out of the bike!
From the ad though, the "needs battery" is always the most suspicious thing...
I'd ask when it last ran, who ran it, how often was it used up to that point, if not very often - why not. You should just try to get a picture on how the bike was used, how often, if the owner ever experienced any problems with the bike, if he knows of any problems that still exist on the bike (besides the flat battery), etc.
Seems like minimal risk on that bike though. I'm tempted to pack up a battery and fly to Tulsa myself and ride it home to Buffalo