[sshanky]

So far I think the best value, even better than Costco, is Sam's Club. Bring them frames and they will trace them and measure your PD, then make you a pair of single vision Pentax lenses with AR coating, for less than $40. Add $60 and you have polarized sunglasses. This is for CR39 plastic which is optically superior to polycarbonate/high index lenses. There is also a great warranty, since Sam's Club will let you return anything practically any time.

You can find most frames for a few bucks on eBay, including popular brands like Ray Ban.

I have bought quite a few pair so far and am super satisfied, especially with the optical quality, compared to the competition's "HD" stuff.