turns out the best he can do is get one for ~ $425. So all you ...lost reps, what gives?
Gonna sell it to him for $200. I think it would sell in a store here for $400. I wouldn't sell it to someone I didn't know for less than $300 so I think that's fair.
With a bit of experience selling boards in the East Coast market, I would say your estimate of its value is probably correct. Maybe $25 high only because of the (well-repaired professionally?) fin box, but the limited-availability of it being a specialty model might make up for that $25 anyway, putting you right back around $300.