If your room has a kitchenette, a rental car opens up the island's surprisingly good grocery scene. Rule number one: if a supermarket is within walking distance of your resort, expect high prices. Shop where the locals refill their fridges.
Dutch side
Carrefour is the main international brand, with a large store near Philipsburg and another in Cole Bay, plus smaller markets at Jordan Village and Porto Cupecoy. You'll find US brands alongside a strong European selection — well worth trying the European dairy. For bakeries, try Café Atlantico in Simpson Bay or Baccus in Nettle Bay.
French side
Super-U offers unbeatable prices (with locations at the Howell Center in Marigot and in Hope Estates) and draws Dutch-side residents over for the savings. Monoprix at Bellevue is the place for fine food. Important: pay in US dollars, not euros — paying in euro, including by card, can cost you up to 20% more.
Price differences are dramatic. The same package of mozzarella that's USD 10.43 on the Dutch side can be about USD 3.30 at Super-U; quality coffee runs USD 5.40 vs USD 1.50. (Canned tuna, oddly, is cheaper on the Dutch side.) Bargain hunters will enjoy comparing.
Reserve a clean, late-model car with VIP airport meet & greet.