Duty-free St. Barts offers liquor and French perfumes at some of the lowest prices in the Caribbean -- often cheaper than in France itself. You'll find good buys, albeit a limited selection, in haute couture, crystal, porcelain, watches, and other luxuries. Gustavia's rue de la République is lined with designer boutiques, including Bulgari, Cartier, Giorgio Armani, Louis Vuitton, and Hermès.
Aside from Gustavia, St-Jean is the island's center of shopping action, with several small shopping plazas along the main road leading toward Lorient: Les Galeries du Commerce, La Villa Creole, La Sodexa, and L'Espace Neptune, each filled with small boutiques. We actually find St-Jean a more satisfying shopping experience than Gustavia -- less of the chillingly pricey luxury brands and more of the real-life St. Barts clothing we covet: flirty bohemian-style kurtas and gypsy dresses; sexy, slouchy jersey separates in dusky tones; gold and silver sandals or bejeweled flip-flops. La Savane Commercial Center, across from the airport, has grocery stores, an electronics store, and a handful of boutiques.
As for island crafts, the little old ladies from the fishing village of Corossol have traditionally made intricately braided straw goods (baskets, bags, bonnets) from the dried fronds of the latanier palm. These delicately woven crafts are for sale along the harborside Quai in Gustavia.
Keep in mind that most shopkeepers open around 9am or 10am but close midday for an extended dejeuner (lunch) that may last until 2pm or 3pm. Closing times are generally 7pm.
There are officially designated sales seasons twice a year, generally the month of May and from mid-October to mid-November. Much of everything is deeply discounted, including couture -- so expect to find some great deals during these times.