If you have a stylish friend he will tell you that sunglasses aren't just made to protect your eyes from the burning sun. He'll say that wearing sunglasses makes you look better, cooler. Dick Moby is an Amsterdam-based brand that makes really cool sunglasses and they also put together this cute video to show how they make them.
I had a pair of 'cheap' $20 Foster Grants my kid knocked off the table and cracked the frame. So I just went and bought a new pair, those cracked in less than 2 weeks. Foster Grant wanted me to ship them in (at my expense) to look at them for a possible replacement. No thanks.
I bought 3 pairs of sunglasses from Dollar Tree for a buck a piece, and still on my first pair after 6-8 months.
Some things are worth paying more for, sunglasses are not one of them for me anymore. JMO