I think there is also an element of education/surprise for the viewers as to what items can have value that you would never consider (like old oil cans, rusted out bike frames, etc). Since the 80's, it seems as though everyone "knows" baseball cards are worth "lots of money," so I could see the producers making a conscious effort to choose other "unknown" items to focus on. That's purely conjecture, but I must say, I really do enjoy the educational aspect of the show whether sports-related or not. Maybe someday I'll watch enough of it to actually retain some of the information
