Just my opinion, but...
What is the point of a book of values if no one in the area agrees? Isn't something worth exactly what someone will pay for it, no more, no less?
When valuing a gun, I look at what it is selling for online as a floor, and what it is selling for locally as a ceiling, and go from there. If used, I look at online auction sites to get an idea. If I am paying close to what it sells for online, or getting more than it goes for online, I consider that a win.
Of course if you have really old guns you want to value then ignore everything I'm saying and use the book.