Apparently there are many fake Shure mics being sold on ebay. The fakes are almost identical to real mics in appearance, even down to the packaging.
There are even fake Beta 52A bass drum mics. My advice is to buy from an authorized Shure dealer if buying them on ebay.
Below is a link to a pdf on 'how to spot a fake' sheet for reference. There are youtube videos showing how to spot them and there are numerous posts about fake Shure mics on 'gearslutz.com' and other sites.
I just purchased a Beta 52A and will check it when it arrives. I was unaware of how widespread fakes are, but I became suspicious because the mic was new and the price was $40 to $50 less than market. I'll update the post with my findings.
[ame="http://www.ziggysono.com/upload/104ShureAgainstCouterfeit.pdf"]http://www.ziggysono.com/upload/104ShureAgainstCouterfeit.pdf[/ame]