srqpete
Like anything it all comes down to condition. Some people feel any markings including the police markings hurt the value of a gun, but police collectors such as myself actually look for them. But then that being said the 3 things that determine value are condition, condition, condition.
Of course rarity also helps. My S&W pre-Model 45 was one of only 20 guns the BPD had and 1 of only 40 (or 50) that Smith ever made so that adds to the value. The Commandos were not rare and there is not record of how many they had but at a guess it was hundreds, so it is condition based.

__________________
Free Advice is never cheap