Antarctica has no stores, no shops, no commercial retail of any kind. The continent hosts only research stations (40+ year-round, 30+ summer-only) operated by national programs. Residents—scientists and support staff—receive all supplies via ship or aircraft resupply missions.
The Antarctic Treaty (1959) prohibits "measures of a military nature" and nuclear activity—but commercial enterprise is constrained by the 1991 Madrid Protocol's environmental rules and the practical reality: no permanent population, no currency, no infrastructure, no supply chain.
Bring everything you need. Expedition cruises provide gear, food, and souvenirs onboard. No ATMs, no card readers, no Wi-Fi for shopping. The only transaction is the one you made booking the trip.