Why not try those cheaper USAF-Sunglasses if you don't mind looking a bit topgunish?
http://www.armynavysales.com/Merchan...egory_Code=SUN
just $ 40
-bayonet temples (will fit under heavy headsets)
-grey lenses (for true colours)
-heavy duty metal frame (but slightly heavy to wear)
found them in the UK too:
http://www.flightstore.co.uk/search....6.item_id.162/