Check out Zenni Optical - an online prescription eyeglass maker. You can get glasses starting at $6.95 and bifocals for under $25. You enter your prescription information obtained from your optometrist and they ship you your glasses within 2 weeks.

They have a large assortment of frames and sizes and can even do sunglasses. The frames are sturdy, but not quite up to the quality of the designer frames you can get elsewhere. They are good enough for everyday use, however and I wore a pair of their bifocals for over a year with no problems(when I had financial difficulties and couldn't afford store-bought glasses).

The lenses are top quality - comparable to what you'd get anywhere else. Lots of options, too. To date, I've bought three pair with no complaints. Give them a try. No affiliation of course, just a satisfied customer!