Video games may be a newer participant in the world of auctions, but trading cards are one of the classic collectibles you'll find being bought and sold. A recently concluded auction on Goldin Auctions sold a complete mint condition collection of 103 First Edition Pokemon trading cards for a total of $666,000 (and no, there has been no eruption of hellfire over this victory here, or in Kanto to our knowledge.)
Starting from its creation in 1996, the Pokemon Trading Card Game has sold over 30 billion cards as of March 2020. It also released two video games for the Game Boy Color, with the sequel being a Japanese exclusive. Like many trading cards, some of them can be worth some major stacks, with some of the most valuable ones including promo cards and the English version's First Edition cards, which were printed at the tail end of 1998. In particular, the 1st edition shadowless holographic Charizard is the most valuable card in that set, with the other 1st edition holographic cards representing another big percent of the set's value. Recently, a now-finished auction on Goldin Auctions sold a holographic Charizard and its other 102 First Edition siblings for a whopping $666,000.
As the page for the collection explains, every card in the auctioned set has a GEM MT of 10, meaning the cards are mint condition, a very high grade for Pokemon cards. In addition to the highly valuable holographic Charizard, some of the other highly-valued cards include the 15 other holograhpic Pokemon in the set, Devolution Spray, and Imposter Professor Oak, a character with his own interesting history. As a point of comparison, in Goldin Auctions' December Holiday Auction, an SGC Gold Label Pristine 10 "1 of 1" Charizard was sold as the first lot for $360,000. We've also seen Charizard go for over $300k at Heritage Auction this year, building on top of when they were going for 'only' $220k in October last year. Buying a box of the set isn't much cheaper then buying the complete edition either, with that recently going for over $400,000 at auction.
So, if you got any old Pokemon cards, it might be worth digging them up to see what they are worth - you might just have your retirement plan there.