And you thought that Nintendo World Championships gold cartridge would make a nice start to the retirement fund. An eBay auction from tjcurtin1 is offering a prototype NES cartridge for the US release of The Legend of Zelda at a Buy It Now price of $150,000, or roughly ten times more than the typical final bid that Price Charting quotes for a typical NWC cart. While it looks like an unassuming yellow chunk of plastic, it's actually a Nintendo of America copy from February 23, 1987 -- half a year before the definitive action adventure reached the US market. The game still plays and can even save its game on the still functional, industry-first battery backup. Just remember that it's not necessarily going to reveal any design secrets from Shigeru Miyamoto or Takashi Tezuka: the seller warns that he can't see any practical differences between the early copy and the (also included) shipping version. Anyone well-heeled enough to buy the prototype is therefore going solely for the collector's value. But for those determined to be the coolest kid on any block about 25 years late, there's only one way to go.