The DSi XL demo video cartridge: an antiquity with a price.

A DSi-only cartridge (a rarity in and of itself) containing nothing but a repetition of auto-playing trailers, presenting games like Scribblenauts, New Super Mario Bros., Flipnote Studio, and other high-profile DS games.  The thought of such an item brings forth the notions of a rare, yet mundane and worthless promotional item; but ebay seller qualitydisc has decided to stick a price on this...rare and desirable heirloom: the auction starts at $399.95.

Happy bidding, I guess.