People who have the rarest collectable stuff are often dicks to deal with, it's a pattern I've noticed before. I guess it's because the rarest collectable stuff often isn't supposed to reach collectors hands, so the people who get them have to be somewhat "flexible" in their attitude to laws/moral values and the way they treat people. It's a double edged sword really.
I'm all for being honest and professional and I do my best to be polite and accomodating even when a problem occurs. But if someone screws me over and isn't interested in making it right then the gloves come off. No matter how little the money owed or how minor the problem, I'll dig my heels in and get as much out of them as I can just to teach them a lesson.