Well for one, its known as a "Regulation Police". Caliber is 38 S&W, I think/based on what you told me (5 shot). I'd have to check a reference for production year but its certainly pre WWII. It was on S&Ws I frame which was later discontinued in favor of the J frame for 38 special (the 38 special was too long for the I frame). The gun eventually became the model 33, much later, after 1957.
Not much of a demand compared to some S&Ws but if original nickel, odd barrel length or in fantastic shape, it wouldn't be worth $100 either. Probably worth $150 to $400 depending on condition and features.
Should have wood grips without medallions, IIRC.
Thats about all I can say without my book. I hope that helps.