Prince William of Wales wears black Oakley Straight Jacket sunglasses during a ski holiday in Switzerland in 2008. These old style Straight Jackets from Oakley have been completely changed (see the latest model on Oakley.com) so for this old model you would have to try eBay.

William's future wife Kate Middleton was spotted with Bolle Boost goggles during that same holiday.

Reference: Oakley Straight Jacket, Black, gold color logo