Just check him out the best you can cluu1 (he has an actual address in a residential area, drive by the area and/or house to get a feel for the neighborhood, etc.)
I am not from that area so I can only guess about price ranges, but a bike that originally sells for $800 and up going for $350 pretty much brand new seemed odd. Unfortunately not every one is legitimate. I've looked at many things using craigslist and walked away from a sale because the story the guy was giving me wasn't matching up.
For instance, one guy was selling a pretty decent car for not a lot of money. I told him I would get back to him after I did a VIN search. He questioned my motives and I told him I do that for all the cars I look at. He seemed perplexed and stated that if he didn't sell the car he was going to drive it down to North Carolina and leave it at his other house. Granted I am looking at this car in a run down shack of a home with 3 other vehicles littering the lot. I walked away with no intentions of doing a search