If you want to buy Sunglasses then buy them from retailers and not online as you can be fooled easily while shopping online.
Some of the sunglasses brand have their own quality marks like the polarized ones which can be checked by customer for gunienity.
If you are afan of Ray Ban then read this review and search the internet how to identify original from first copy as there are very minute and rare differences between original and first copy or original and fake.
Dont buy local sunglasses as they will not protect neither heal your delicate eyes and this products can be your next trouble.