Hi Nick,
this guy is blatently trying it on with you which is pretty shameful,
I've bought a fair few XX's lately and that is a £75 car max, it's no mint collectable shelfer and he doesn't exactly care that much about it to leave it in that state, i know the sentimental is playing on you but nobody else would pay anywhere near that for it so you kind of have the upper hand!
Find yourself a clean one and twist Tony Evdoka's arm to get the airbrush out again