I just found this on Craigslist. The guy you're talking about is in IL.
This looks fairly nice but they all look better in pictures. I'm trying to contact the seller but he didn't provide a phone# so it's email only.
200 was only produced 1975-76 and has the 8 HP K181QS engine. They are rare but don't seem to be overly sought after by collectors. $150 is probably reasonable given the engine issues. Parts for the motor are available but pricey ($304 for a crankshaft ). I've got one torn down on my bench right now with a scored crank.