This book is a tremendous resource for all things S&W.
The description of the gun models, grips, boxes, sights, options, engraving, scarcity, serial number dating etc is more thorough than any other volume on the subject. I am sure somewhere in the beginning of the book there is mention of pricing. Prices are based on a period during and mostly prior to the publishing of the book. The values stated are to be used as a general guide adjusted for the time frame of the auction, sale or research.
Collectible gun prices are usually fluid, and mostly go up. The market determines the price (willing seller/willing buyer), not SCSW or Blue Book of Gun Values.
This forum is as about accurate as you are gonna get. Post a question about an item's value and within a short period of time, collectors and shooters from across the country will tell you what they recently paid, what is a good deal, what to avoid and on and on.
Use the SCSW as a guide when purchasing so you don't get ripped off. i.e. Who would have known those grips are not correct for that gun. It's all in the details. Just my opinion, but this type of view has enabled me to build a collection of quality guns at reasonable prices.
To me, the SCSW is worth every penny I spent on it.
Cap