I recent got these and LOVE them.
www.wiley-x.com
Wiley-x SG-1
http://www.wileyx.com/sg1.php
They can be sunglasses or goggles and have interchangeable lenses. They say they support Rx lenses. I don't know how its done or the cost though.
Ironically, though, I have an eye appointment today and was planning to check with the opitcal area about what it takes and how much it costs to get the Rx lenses.