In my experience any books about antiques that give price guides are only ever current when they first go to press.
Trends can change in the collectors market, just look how the price of Ivory goods has dropped, now that it is frowned upon.
Also you are unlikely to find a book that covers all types of locks from all countries.
BTW what country are you collecting from.
Are there specific types of locks you want or dont want.
There are some books around for say, padlocks, like:
Frank Arnall’s “The padlock Collectorâ€Content: subtitled: "illustrations and prices of 2800 padlocks of the past 100 years", includes a listing of lock companies and padlock manufacturers, types of locks includes Scandinavian, lever push key, 8 & 6-lever, railroad, combination, wrought iron lever, brass & iron lever, pin tumbler, miniature, locks with logos, etc, NO INDEX, with values
Give us a bit more info and I'm sure more suggestions will flow.