Maui JimMen's and Women's Stingray Polarized Wrap Sunglasses

How can a buyer be assured they are authentic at $60. less than standard $119 or 129

I tried these on at Cabelas (I am a woman), and they fit perfectly. My question is, do these come in one-size-fits-all?

Do these have glass lens?

I see the same model on the Maui Jim website for $229. What's the difference between this one and the one listed on the Maui Jim's website ?