Around $ 500 - $ 600 in my area is about right as well...
The dash 7 's began in 1994....but in the dash 5 series they eliminated the cylinder counterbore and pinned barrel ( that a lot of guys like )...so its a little more difficult to sell than earlier versions.
S&W eliminated the Nickel finish on this model in about 1992...so if it was an earlier gun ( from no dash thru dash 4's ) and in Nickel ...it would be about
$ 200 more...and a faster sell, at least in my area.
So as you look around for used model 19's in your area...I would look at the prices, and condition, and evaluate those engineering changes ---and see what's happening on pricing in your area. ( and probably look at the prices on the model 66's ( basically the newer stainless version of the model 19 in a K frame )...
But all of the 4" barrel model 19's are very nice shooting guns.../ don't let it go too cheap.