What's wrong here?

Whats wrong here????????? I was browing through ebay today and saw this item for sale.The product is a memory stick: Alienware 512 MB PC2-4200 DDR2-533 533 MHz Laptop Memory Ram AW000043.....Now look at the price after a 20% savings! What the hell!!!!!!!!!!!!!!!!!!!
http://www.ebay.com/itm/Alienware-512-MB-PC2-4200-DDR2-533-533-MHz-Laptop-Memory-Ram-AW000043-/380698443010?pt=US_Memory_RAM_&hash=item58a3653d02