Those sunglasses are the Chanel 5018 Half Tint Glasses.... they can be ordered directly from Chanel since they seem to be out of stock everywhere else.
These are two seasons old and sold out everywhere -- I doubt that you can order these, even direct from Chanel.
If you're willing to fork out upwards of $1,000, you might be able to find a pair on eBay every now and then. BUT, if a pair pops up, have it authenticated before bidding - there are fakes of this style.