[Lordstan]

I think it depends on your reason for buying the book.
If you want it because you like the Yanks and that era, and are going to keep it, I think $250 is not unreasonable.
If you want it to break it down for resale, I think $250 is too much unless there is some hidden rare gem in the book. You would make your $250 back, but I doubt there would be much profit. Plus in order to sell them for good money, you would have to break it down and sent it to one of the auth companies for certs. If you combine the $250, plus the cert costs, I think there would be very little left over.
I agree with Dr Cycleback on the bump for vintage sigs, but nowadays I don't think there are that many people out there that are going to give a whole lot extra for them. The super rare sigs would absolutely get the premium, but for most of the regular Yanks and Sens, I think people will save their money for something rarer.

JMHO,
Mark