I'll agree with everyone here and say that is too much.
As far as being under powered depends on your intended use. If you do most of your fishing 10 minutes from the launch it's not a big deal. If you running out to the shallow platforms.... well I'd want more motor to get it done.
I'd say a fair value is about $20,000
He may have set his price based on this.....
http://www.nadaguides.com/Boats/2008...0261242/Values
http://www.nadaguides.com/Boats/2008...-Motors-Values