A New Prescription

I've been getting pretty bad headaches from my glasses lately. I think I might need a new prescription. It's been 2-3 years since my last eye appointment...but now, I've just turned 23 and that means I am no longer on my parents' insurance. What to do? I wish eyeglass stores would list their prices online (they probably do somewhere) because I don't really want to go through the trouble of calling different stores. Does anyone out there know how much it typically costs to get a new pair of glasses (non-fancy ones) without eye insurance?