Well, it depends on what "refurbished" actually means! I'm in Boston, too, and have in the last year bought several Sports and a Superbe, all for $100 or less. Only one really didn't need any work (and that was a lady's Sports, which tend to go for less), the others were in various states of need refurbishment.

Have you been over to the OldRoads shop in the antique mall on O'Brien Highway in Cambridge? They usually have 3-speeds in your price range and do solid work to make sure they're ready to ride.