Why is this flash selling so cheap?

Http://www.ebay.com/itm/271162387505

All other listings for it go for 200+?

Its cheap because its junk. Its unlikely that it will allow use of your Nikon's TTL and i-TTL flash circuitry (look in your Owner's Manual for an explanation). There's always a possibility that a cheap flash like this could short-out internally and damage your camera.

Obviously I've no idea what model of Nikon DSLR you have but if you paid 600 or 700 dollars or more for it why would you want to buy anything other than a Nikon flash to use with it? Invest in the Nikon SB-700 AF Speedlight (about $330.00) and you'll have a flash made to interact seamlessly with your Nikon DSLR. With reasonable care you'll be using your Nikon flash many years from now. The cheap one you saw on eBay might not last a year.

Always remember this: "A cheap flash/filter/lens isn't good and a good flash/filter/lens isn't cheap."

Check out amazon for the same flash… Price $47.45 and read the reviews, and you will see why it sells for a low price.

Best wishes