I bought 20 pairs of $2 Oaklys when in China.
As they go over the side I laugh.
I just paid (2 days ago) $208 for a pair of Oakley polarized sunglasses. This is my third pair, and so far the cheapest. They hold up well, and my theory is the more expensive the better you will take care of them. My first pair was well over $300, I've had them six years and still love em.