When it comes to online purchases, you're unlikely to find any other website with quite the same variety as eBay. You can quite easily buy some custom made birthday cards for a few dollars, or a rare prototype The Legend of Zelda cartridge for just $150,000, which is the price of a small house or expensive sports car.
The seller, tjcurtin1, states in the eBay listing his belief that this may be the only copy of this item in the world, and has posted a number of images and a video to boost claims of legitimacy. In terms of the value and rarity of the cartridge, the listing says the following.
This is without a doubt the pinnacle of my collection and I challenge anyone to come up with anything more important in the video game collecting scene. Stadium Events? How many carts are out there? Hundreds. NWC Gold Cart? Again how many? There is one Prototype in the world for the NES Zelda, one prototype that started the launch of a generation of gamers and you are viewing it.
Various efforts to show authenticity are made, such as explaining the label as showing a date merely months before the title launched and demonstrating the TEST circuit board within. The cart itself is yellow as opposed to the retail gold, but the listing is also offering a boxed copy of the retail title as an extra. At the time of writing bids have been submitted, but obviously none at the target price, and it'll be interesting to see whether anyone is actually willing to pay the full amount. The seller has also produced a video, below, of the prototype cartridge in action and then disassembled, though collectors may want him to stop putting a cart allegedly worth $150,000 into a yellowing old NES.