It appears to be a nickel S&W Model 19, specifically a 19-5 made sometime after 1982 as it lacks a pinned barrel. I don't recall when the 19 was discontinued; sometime in the late 90s IIRC. Looks to be in pretty nice shape too. With a 4" barrel in my state, such a gun would probably go for $500 to $550 or so (a blued version, which is how most Model 19s came, would be $25 - $50 less, FYI).
These are fabulous revolvers, built on S&Ws medium K Frame. I've got a 4" .38 K Frame, and would love to add a 4" .357 K Frame model 19 (blued) one day. Just limit the number of hot .357s weighing less than 135 to 140 grains and the gun should give years of reliable service.