The University of Waterloo Library does not offer evaluations or appraisals.
The reference collection in the Doris Lewis Rare Book Room includes several guides to recent auction prices, prices in dealers' catalogues, etc. Book Auction Records, American Book Prices Current, and Bookman's Price Index are among the standard guides to used book prices. Please ask staff in the Doris Lewis Rare Book Room for assistance.
Many antiquarian book dealers who specialize in valuable and collectible books perform evaluations or appraisals, usually for a fee. Consult the Yellow Pages under, "Book dealers--Used & Rare", for names of dealers in your area. There are several directories in the Doris Lewis Rare Book Room which list names, addresses, and specialties of antiquarian book dealers.
There are many sources of information on the Internet about books and book dealers. One starting point is the Antiquarian Booksellers' Association of America.
For advice about what to do with old books in your possession, check Wondering what to do with your old books and documents?.