Second gen are worth more than first gen! I would suggest a price range of 40-90 and 60-200. Though I think demand has gone down a little which can make prices lower, but I'd say you'd still have a good shot.
As I saw from the edits you made, the consistent standard on this wiki is to use "Furbys" when referring to Furby in plural.
I'll try using that in my edits from now on, but could this be standardized somewhere in the wiki guidelines pages?