These are authentic, and the are not made in the USA. Some of the discounted pairs of Costa sunglasses are made over seas. Costa states that "most of our Costas are hand assembled in our Daytona Beach, Florida workshop."
You can view Costa FAQ here:
Where are my Costas made?
While we receive parts for our sunglasses from all around the world, most of our Costas are hand assembled in our Daytona Beach, Florida workshop. Because we have yet to find a machine that does the job as well as a real, live person.
Your Costas are examined by no fewer than eight pairs of eyes before they ever shield yours. It's the only way we know how to keep the high standards we need to confidently back every pair of Costas we make with a limited lifetime warranty.