You should buy a Beckett magazine. You can find each card and see how much they are all worth. You might have some high value ones
It depends on condition and players included.
It's tough to say. Depends on the players, condition, and rarity. Rookie cards are the best bet, but the card market is pretty weak now. Best bet, get a price guide see what you have. Sell them online. Most retailers will only give you 30-50% of the value.
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