There are three price books, the NADA RV Guide (not the free one online!), the Kelley RV Blue Book, and the Black book. Each dealer (and bank) chooses what one they prefer to use for valuations. NADA seems more popular in the East, while Kelly seems more heavily used in the West. No rhyme or reason that I know of.
A dealer doesn't necessarily give you the exact value in the book, but it gives them an idea of what the market price is.
Black Book Auto | Recreational Vehicle | Lender Solutions
Recreational Vehicle Blue Book
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL