Recently, there are some counterfeit cases happened on ebay. Huge capacity with super cheap price is always a typical trap...
http://www.kingston-blog.com/en/bbs_thread...?gid=16&aid=951
http://www.kingston-blog.com/en/bbs_thread...?gid=16&aid=937

Here are some useful microsites for verifying:
Kingston Technology Company - Company - Memory Verification
Search For Genuine Kingston Products