These cameras are so rare that IMO determining a fair selling price is going to be tough, but... There was a discussion some years back on the LFPF where it was mentioned that these cameras are typically listed in the $3,500 to $8,000 range. To my mind, the trouble with selling in this stratosphere is that there are several new options available at the lower end. I guess someone would really have to want this model camera, specifically, with price being not object.
I wish you all the best, if you decide to sell it.