Visionworks (with 700+ stores nationwide) is having their rare (but great) sale where two pairs of single vision eyeglasses (frame and lenses) are $49. It's $89 if you want two pairs of progressives.
The frames come from their "value" collection. The better deal is picking clearance frames that are marked down to $69.95, and getting two complete pairs of glasses with those frames for $49.
Sale ends June 30.