I love my now 20 year old Revo sunglasses.
I bought them for about $200 way back in like 1988.
Before these, I always enjoyed Rayban aviators most.
Revo was made famous by the work they did for the Nasa program.
http://www.revo.com/
click on the technology section.
This got my interest, and after putting on a pair...I've never had better.