You can use an auction or classifieds website like Gun Broker, Auction Arms, Guns America, et. al to look at what prices are being asked for comparable models being sold, or you can simply take it to a gun shop and have them give a quick appraisal. If you go with the latter option, avoid pawn shops and visit a few different gun shops.
Which model? Value varies with make, model, and condition.
Depending on condition, and blued or stainless, about $400.
100-400 USD
Your Smith and Wesson revolver was made in the year 1985.The value will be between 375-600 dollars depending on overall condition of your revolver and a good bore.
You will have to spell out the maker's name.
50-350 USD or so depending on condition.
A K frame, stainless steel revolver made between 1982 and 1986.
For a Smith and Wesson revolver in stainless steel that shoots short bullets, you might need a 380 caliber pistol or a S&W 32 caliber revolver.
250 USD
The smith and Wesson model 64-3 which was made from 1977-1987 is valued at 215 dollars for a revolver in good condition,250 for a example in very good condition,285 for a revolver in excellent condition,and finally 400 dollars for a fine example in almost new in the box condition.
In excellent used condition, this would be valued around $475, but that value falls for lesser conditions.
Stainless Steel Revolver