Cheap Ray Bans? Your best bet is Costco. They carry those and many other legit brands, like Maui Jim and Serenghetti, for less than $100 and are all polarized. If you're not a member, you will have to pay at least $55 for that, but you'll still end up ahead and likely find lots more ways to save money there.
NOTE: I don't work for Costco nor am I tied to them in any way. My brother-in-law does now work there but this was only after I'd been a customer (and bought sunglasses there) for a long time.