The answer is that the value varies a great deal depending on exact version of the gun, where you are in the USA, the gun's condition, and current market for that model.
The online auction sites and their completed sales are probably the best indication of value. You must adjust for condition, and where you are trying to sell it.
Clearly, a forum like this can't give accurate estimates without knowing details. Gun shops have to make a profit, and they'll offer something different that a private buyer would. They'll also sell it at a markup for profit, establishing an approximate insurance value for replacing one.
Dealer's will 'give you' maybe $100. Then, put it in the gun case (untouched) for $500 to $700.....depending on condition. They say "I have to make a living....ya' know???" I don't like gun dealer's very much!!!!! 'Gun Crooks'.....would be more accurate!!!! Bob
I’d hold onto it unless your strapped for cash. I just started buying smiths and they have gone up in value a lot just since 2015. To say nothing of any sentimental value. If your looking around for real world value Armslist.com and search 19-4. It’s hit or miss some stuff is wildly overpriced. Vendors definitely charge a premium. Gunbroker is another but I feel like they’re high.
Around here the market has dropped on blued Model 19's in the 4 and 6" barrel lengths. The 2.5" still hold value well. Everyone wants Stainless Model 66's. A blued 4" Model 19 with rubber grips would be around $500. Maybe $550 if extremely nice. Original Grips would add $50. If it were my father's gun, I doubt seriously I would ever sell it unless I was really hurting for money.
Target trigger..target hammer..pinned barrel,recessed cartridge holes..all forged...plus a duty belt/holster..around here its a $700 revolver package and won't last 3 days on Armslist,especially if I see it on day 0ne..
As you can see, different folks in different areas of the country have differing takes on what it would be worth to them. I am no different and here is my take on it's value. What you have is a pretty much bog standard M19-4 missing the original grips. It might very well be a $600 gun with the stock grips, but missing those and combined with pictures that don't really tell me what the finish condition is actually like, I personally wouldn't value it at more than $450 based on the information and pictures provided.
Bear in mind that original factory target stocks are fetching $75-$125 on Ebay, so I decrease the value by that amount. Properly cleaned with the factory grips and decent pictures may change my estimate.