My God. $25.02.... It probably went on the retail shelf for $35 or so. A hefty sum during the middle of the Depression.
Congratulations. You have one of the rarest of all Smith & Wesson revolvers.
To say that I am envious is the understatement of all time.
You probably want to get more than one appraisal, as it's rare enough that you're probably going to run into problems finding people who are familiar with it, but with the authenticity verified by S&W, and its overall excellent condition, I think 3 Gun is probably right, it could top $10,000 in the right auction.
Now if you only had the original box, paperwork, and bill of sale.
My suggestion at this point would be to get in touch with the Smith & Wesson Collector's Association to see if they can put you in touch with a proper appraiser.