It looks like Sierra Trading Company has a few more great diamonds among the poop. Randolph Engineering is a Made in USA company that has been making sunglasses for the US military since the 80's. They go head to head with anyone in terms of quality and I've been trying for a while to suppress the urge to supplement my classic Ray Ban Aviators with some Randolph Engineering.
But at ~$53 and $73 for non polarized and polarized versions in an array of options (Aviator - see right, Concorde - above, Sportsman, and Crew Chief), they are a rare value in an online market that usually regulates sunglasses prices pretty consistently. If it's good enough for Don Draper, it's good enough for you.
Check them out here.