As to the Transition lenses at Costco, they are completely clear indoors, just the right amount of tint outdoors and begin to darken instantly as soon as you step outdoors. It also helps protect against harmful blue light from digital devices, screens and the sun. Moreover, it also helps reducing glare, eye fatigue and eye strain. It also could blocks 100% UV rays.
However, as to the cost, it depends on the lenses you choose, whether you choose high index lenses, or progressive lenses? Take me for example: when I was pricing out my eyeglasses, which were standard polycarbonate single vision lenses, she said it would be an extra $35 for the Transitions lenses. I asked her how much it would cost for 1.67 high index lenses with Transitions and she said that the 1.67 high index lenses are $100 and with Transitions they would cost $160.