This is an old fart link, but I'm sharing it because I know there are a couple people here who use glasses.
http://www.zennioptical.comJust over a year ago, I bought a pair of prescription sunglasses and one regular pair and it cost me about $550. Both of my bosses now have ordered glasses from zenni. My main boss just got 3 pairs of glasses with progressive lenses (like bifocals without the lines) and one pair was a pair of sunglasses. With the frames, lenses and shipping, the 3 pairs cost $140.
Anyway, I am thinking of buying some extra glasses from this site. All you need to do is visit your eye doctor and get your prescription, then zenni will send you your glasses in a week or two.
Good stuff. Glasses are fucking expensive, usually.