mscottc said:
Actually even easier. Take the causeway from the end of the runway closest to Simpson Bay that crosses over to Cole Bay. At the Cole Bay end of the causeway turn right, and just a very short way after that turn you'll find one of the two large Grande Marches. That's the place to stock up. Just make sure one person stays with the car while someone else shops. When you exit the Grand Marche, turn left and follow that road to Marigot, on to Grand Case and then into Orient.

Google Maps view of Causeway

The big white building just south of the causeway terminus is the Grande Marche I'm talking about. And north on The Rue de Hollande, is the way to Marigot.