I have bought one of these Energie shirts from Hong Kong over eBay before, and they look and fit authentic although the material is questionable. Another things is that the buttons are generic, and most designers have their name etched on the buttons.
Of course in my case the seller never claimed his PayPal so the item turned out to be free
I also purchased a pair of Prada jeans for $30 (with $20 shipping though) from another Asian seller, this time Thailand I believe, and these are definetley authentic down to every button and stitch and feel great (like Prada should.)
The bottom line is be cautious of buying any big ticket fashion items from Asia since a lot of fakes are indeed manufactured there, but you are safe to buy anything relatively minor like belts, club shirts and jeans. Even if they turn out fake chances are nobody will know.