When Magic: The Gathering hit the scene in 1993, it changed the world of trading cards forever.Finally, there was a trading card game that older kids weren't embarrassed to be seen playing. Today, 20 million Magic players around the world are still collecting and trading their cards. But even if you've given up on the game, you might want to dig up your old collection.Certain magic cards are worth a bundle online. We've researched the average prices for 13 of the most valuable cards (in good condition) on MTGPrices. See if any of these are tucked away