Every once in a while a Nintendo World Championship cart will pop up for sale. These carts were given to the contestants of the 1990 NWC. There are about 100 grey carts and 20 something gold carts. Grey carts can pull anywhere from 5-10k, while gold carts can pull 10-15k+.

This particular one is claimed to be cart #1 and at $25k is probably the most expensive NES related item to date.

Crazy madness.

Auction link: Here

NWC Reproduction link: Here