I've never hiked the Alps but took the Swiss Rail System. REI should have some decent gear. Insulated boots polypropylene layers will depend on the the weather vs activity. Interesting time he picks to hike the Alps. I'd talk him into skiing instead this year and layer up toasty. I've been in -40C and anything you'd buy at Old Navy will likely get you killed. I tried something similar one year on a trip to northern Ontario, wayyy North. I learned real quickly to buy clothes there local to that climate. Good gloves and head cover also.