Buying glasses over the internet requires having measurements taken by your optometrist or ophthalmologist, in addition to having your exact prescription. Once you’ve done that, it’s mostly a matter of choosing what frames suit you and ordering. I’ve found it very practical to have extra pairs of glasses around, especially for kids – and if you can get them so inexpensively, it’s really worthwhile.
Optical4less has glasses starting at $15/pair. International shipping for a single pair is $8, but if you order 2 or more pairs, the shipping is free. They do charge an additional $59 if your cylinder is lower than -2.75 or higher than +2.75 and $3 for each degree of prism correction on each lens. Of course, they’ve also got other options that can make the glasses more expensive, but you can actually get away with 2 pairs for $30, including free international shipping, if you go for a no-frills look... Optical4less also sells Acuvue, Bausch&Lomb SofLens & FreshLook Colorblends contact lenses starting at $16.25 a box (although, interestingly, the links from this page take you to 1800contacts – which also ships internationally...
Goggles4u also sells prescription glasses and sunglasses. It seems like their search is easier to use (you can plug in the width, height, bridge & other measurements & it lets you know what frames meet your needs). The glasses I needed ended up being $29.99, including free shipping.
Zennioptical offers a complete pair of prescription eyeglasses starting at $8. This includes frames & lenses with full UV protection, anti scratch coating,;a glasses case & microfiber lens cleaning cloth. International shipping is $5 no matter how many pairs you buy! Having your glasses tinted costs under $5 and they’ve got pure titanium frames starting at $39.95.
Know of any others? Let me know!