My guess is that in a zombie apocalypse, the value of a Colt Python is the utility of the weapon. There would be no gun auctions, and one revolver probably wouldn't be "worth" more than any other revolver. A Taurus 9mm with plenty of ammo is going to be worth more than any Colt Python safe queen with no ammo.
If Zombies were coming, I wouldn't cringe one bit if a Krieghoff K-80 was used as a club.