Performance sells something called the Radial II with three different lenses (clear, amber and gray) and a prescription holder that snaps in . You have to take it (the RX holder) to your optomitrist and have your RX made and put into the little frame

http://www.performancebike.com/bikes...0_20000_400025

Their site says out of stock, but I was in my local Performance store recently and they had a lot of them. Reasonable price, but that varies depending on how much your lenses cost.

use mine every time I ride and like them a lot.