I bought my Sennheiser MX-985 from:
Ebay seller bigbargainonline, who has 10,000 transactions and 99.9% pos feedback
Sennheiser authentication website doesn't work with their box. That's what got me worried. HOWEVER, the seller has now told me that Sennheisers from China are governed by a chinese authentication website, located here....
Of course, it's all in chinese, so I am having trouble authenticating. But the fact that he showed this to me and showed me which sticker on the box to check is a positive sign.
UPDATE: Sennheiser USA says these earbuds are genuine. I never could use the Chinese website, so I mailed them to Sennheiser in CT. They were VERY nice, friendly and helpful.
Happy Ending. Whew. Bigbargainonline, sorry I doubted you.