I got my XS650 the same way. I just happened to contact him right after he posted it. People were clamoring to get it at $400, sight unseen. It was pretty rusty and corroded from sitting in a damp garage, but I put gas in it, and hooked a battery to it, and it started! Ran like crap and gasoline was pouring out of one of the carburetors, but it started and ran. Mostly, all I had to do to make it road worthy was replace the corroded floats & clean the carbs, rebuild the front caliper, (leaking,) put on new tires and put in a battery.
Reminds me, I have to pull the rotor out of it today and ship it off to a guy that rewinds them.