I take my sunglasses pretty seriously. Have a pair of Costa Del Mar for social occasions and fly fishing:
And I keep a pair of Torge from Amazon in the truck for high potential damage situations and everyday use:
Costa Glasses: $300.00
Torge Glasses: $22.00
If I learned one lesson with good sunglasses its treat them like you do your clothes. Don't wear your Brooks Brothers khakis when cutting up a cord of wood and don't wear your Costa Del Mar sun glasses when mountain biking.