Read up on Luxottica if you want to know how a product with about $5 of materials and $5 of manufacturing costs gets retailed for $150. Short story: Luxottica is a sunglass monopoly that owns Ray-Bans, Oakley (bought out a few years ago), many other brands, as well as retailers like Sunglass Hut, Lenscrafters, etc. etc. Somehow they've managed to convince us that sunglasses should cost this much...
Sorry for the rant, but it's a pet peeve of mine.
Alternatives: I've been happy with the sunglasses at Performance Bike (
www.performancebike.com), and there's usually a sale going on.
7 or 8 years ago I also bought four or five sunglasses from Sunglass Warehouse for about $5 apiece. I have a pair stashed in the car, one pair that stays in my hiking backpack, etc. They're so cheap that it doesn't matter. Incidentally, I read up on UV blocking in sunglasses, and apparently the chemical that provides UV blocking is so cheap that there's no reason to lie about UV blocking. At any rate, I haven't had any trouble with my cheapies so far. They feel and look cheap, but they work just fine.