The Power Pad wasn't Nintendo's innovation though; it was Bandai's. Their Family Fun Fitness Pad was bought by Nintendo, along with Bandai's Stadium Events. All copies of the title were immediately recalled (to be dubbed World Class Track Meet), and to date, only around 10 copies of the US version are known to remain. It's a precious piece of video game history and industry dealings, and people are willing to pay $41,000 for it, maybe more.
A seller on eBay has apparently just uncovered a copy at a yard sale (of all places). His auction consists of a brand new copy of Stadium Events, never once unsealed from its value-multiplying plastic. Sealed games amongst the collector community are expensive commodities in most cases, the more sought after or uncommon the title, the more it hauls in.
The last sealed copy (one of now two in the world) was the vaunted $41,000 game, and this seller seems to hope collector inflation will bring even more. Time will tell.