Many Lacoste shirts on Ebay are fakes, but there are the few that are authentic.

Authentic Lacoste Polo Shirts:

• Have a Devanlay Care Tag inside the bottom left corner of the shirt.
• Have a Crocodile on the left breast of the shirt, facing outward.
• Have a placket with 2 buttons and the buttons have 2 holes, rather than four.
• Are designed in France and made in Peru by Devanlay.
• Have a European size number, for example: 4 (small), 5 (medium), etc.
• Run small to fit.
• For men, polos are 100% cotton.
• Do NOT say Lacoste on the buttons of the polo shirts.
• Have an open hem at the bottom of the shirt, unlike Ralph Lauren polos that have vented hems.
• Tags for short sleeve solid color shirts are listed as $72 and $85 for striped shirts (unlike many fakes that are listed at $79).

For the record, when buying authentic Lacoste Polo Shirts make sure the Crocodiles are sewn on straight, are bought from a US or European citizen (do not trust shirts that come from China, etc.  They are most likely fakes), and follow all of the guidelines I listed above.