I, too, have an expensive vision habit: bifocals, and single-vision middle-distance specs for the computer. My bifocals typically cost about $300 Canadian for the lenses alone, and I need new lenses almost every year. Among other rather serious problems, my eyes are also very, very sensitive to light.

One way I found to duck some of the expense is to wear those bulky over-the-specs sunglasses they make for folks with cataracts. They're both cheaper and safer than prescription sunglasses -- I can snatch them off my nose when driving into a tunnel or a parking garage, and slap them back on again when leaving. With prescription sunglasses, any marked change in light conditions forces me to to take off one pair and put on the other, a process that makes me a great menace to navigation for up to 10 very long seconds.