Its a trade sale which increases price (and has to as the trader not only need to draw a profit but needs to cover his increased liability under SOGA compared to a private sale)
Its a desirable colour
Its low miles, which some people will pay a premium for
I think its strong money, but I dont think its over priced as such, its just a case of if you want a car in that colour with very low miles and dealer backup, then pay for the priviledge, if you dont then find a cheaper slightly leggier private sale one.