You might try checking your local library or book store for reference books on board game values. I found a list of highly recommended titles. If you can find copies of any of these, perhaps it could give you an idea of the value of your games. Hope you find what you need!
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Games: American Boxed Games and Their Makers, 1822-1992 : With Values by Bruce Whitehill
Board Games (Schiffer Book for Collectors) with Price Guide by Desi Scarpone
American Games: Comprehensive Collector's Guide by Alex G. Malloy
Board Games of the 50's, 60's, and 70's: With Prices by David Dilley