In 2007, a Nintendo World Championships 1990 gold cartridge sold for $21,400 in an online auction. The listing's original price was $24, and was listed by a father who was selling off his son's old possessions after he died during the Iraq war.
Only 116 Nintendo World Championship cartridges were ever created: 90 grey cartridges and 26 gold cartridges. The grey cartridges were given to the competition finalists, while the 26 gold cartridges were given to Nintendo Power contest winners.
There's an unused song in the data, which was presumably supposed to play on the title screen which features no music in the released version.