A friend of mine recently came across a box purchase prozac online of older (1980’s and on) baseball and other sports/trading cards. Most are well known brands (Topps, etc.) and almost all are sealed packages.

Other than searching through ebay for each individual pack/card/set, or trusting a local memorabilia dealer, is there an efficient way to find out if these cards are worth any value? Or would it be better to open the packs and search for uncommon cards?