"I've been looking at 66s lately and see three basic price ranges: $400ish for guns with lots of use; $550ish for "cleaner" guns but maybe with burring on the screws indicating past work; $800ish for really clean specimens."
You are looking in the wrong places.
I just checked Gunbroker - 4" 66s for $500 , snubbies for $600.
They looked in great shape.
Maybe add $75 for a really sharp looking one.
More than that is TOO MUCH for a shooter.