Sorry to hear of your situation SCM, this is quite sad. Worst thing that happened to me in 15 years of online selling was ending up with one of those fake Russian knock off Leicas that circulated in the 90's.
Looking at his posting history his posts are primarily re-tweets from twitter which is probably on auto to post on Facebook. His few actual posts sound like he suffered some sort of Bipolar breakdown which could contribute to the being ripped off situation. It looks like he has been on APUG since 06 and has had other sales that were successful. Personally if it were me, I would make the situation known publicly on his Facebook/twitter/etc so his friends actually see what happened. It may help urge him to take action.