A 1999 Pokemon card of the creature "Charizard" was sold for $420,000 during an auction last week. It's one of 121 such cards to be given a "Mint 10" status, meaning it's in brand-new condition.

Out of thousands of Charizard cards from this era, only about 121 are considered to be in mint condition. ... the artist who created the original Charizard artwork.

Here are eight Pokémon cards that have become absurdly valuable, and why collectors are willing to pay ridiculous amounts for pieces of cardboard.