In 1990, Nintendo toured the United States with a promotion tour called Nintendo World Championships. The tour landed in over a dozen large cities and saw gamers competing for the highest score in Super Mario Bros., Rad Racer, and Tetris. Each event was attended by thousands of hopeful contestants.
Prizes given to the contestants ranged from commemorative t-shirts and baseball caps to college scholarships. Each of the 90 finalists was also given a copy of the World Championships NES cartridge. This cartridge has since become a very sought-after collector's item often selling for several thousand dollars on eBay. There are both grey and gold versions. The gold version is considered to be rarest with only 26 suspected to exist in the world. And guess what, there's one copy currently up for sale on eBay. Consider yourself lucky if you can afford the $20,000 asking price.