For value guides (and let me emphasize "guides") the Blue Book for modern and some antique guns and Flayderman's for Amerian antique guns are the best. The latter is rarely up to date, because it comes out only every couple of years.
Specialist books rarely pay off for the beginner. Sure, you can pay $300 for the three-volume set of Pistole Parabellum by Goertz and Sturgess, but unless you collect or deal in Lugers, the cost is not really worth it.
For the real newbie, something like Dudley Pope's "coffee table" book, Guns, presents the whole picture, from matchlock to magnums in a readable format.
Jim