My first thought was it is high.........looking at other sales of B7800 and with the attachments.....13K might not be too bad of a deal considering what you are getting. Private sale or dealer?
I would say buy it.....offer less - bring 12K cash. That many hours....barely broken in - it would be a new tractor without all the new price tag......
find out what fluids have been changed before, even at $13,000 it seems to be a great deal with all that comes with it