Here is a quote from the ebay listing.
Up for sale is a genuine Nintendo World Championships 1990 grey cartridge. It is in good condition, works perfectly and is numbered #215. There were probably about 200-300 of these created and even fewer survived to this day. I received this game about 6 years ago in a private trade. These are quite hard to come by, as you can imagine.
It’s listed for $10,000 or best offer. You can put in your offer here.
Video Game Trader magazine & price guide is a quarterly print publication dedicated to classic and retro video gaming. VideoGameTrader.com serves as a companion site to the magazine. An iPhone app is also available by searching 'video game price guide' in iTunes App Store. 
