Very nice gun and the photos are good enough to allow pretty close examination. The workmanship appears to be excellent in all phases. I would expect its value to act in a similar fashion as many Spanish guns--sharp depreciation upon purchase. One ploy you might try with the sellers: in the future would they allow the full purchase price of the gun back in trade for a equal or higher valued gun if returned in the same conditon as purchased? If so, get it in writing. I have made this type purchase with a couple dealers though haven't exercised the option.

When an old man dies a library burns to the ground. (Old African proverb)