You guys are sadly deceived if you think you can waltz in and pick up a gun like a Model 66 for $300-$375. Regardless of what sights were put on it after the fact, the only pistol you can get in that price range is a used Taurus!
People who buy those guns to shoot will find benefit in better sights. For those who want to tuck it away in a safe in the original condition, they won't pay what a shooter will. So don't wait for the price to drop or insult the owner by asking him to part with the gun for three hundred bucks. I can't imagine why one would want to part with such a gun unless he or she was otherwise being forced to cannibalism or paying for momma's chemo.
For the money, the deal looks good. Me, I'm holding out for a mint 66 with a pinned barrel, counterbored chambers, stamped sights and black rear sights. No one in their right mind would want to part with such a revolver unless the barrel was screwed in backward, but still, people who sell these classics will regret getting rid of them. They just don't know it yet.