The KIRK MARKET (413 Eastern Ave.) is a great supermarket located on the way from Crescent Point to George Town. You will need a car to get there because it is a couple miles going South on West BayRoad.
You can also buy bulk items at COST U LESS (51 Lime Tree Bay Ave.), located about a mile north of Crescent Point on West Bay Rd.
Downtown George Town is very picturesque and offers many Jewelry, Duty Free, souvenir and clothing shops.
All along West Bay Road (running parallel to most of Seven Mile Beach) you will also find numerous shopping malls, with smaller grocery stores, liquor stores, clothing stores, dive shops and dive operations, restaurants, etc.  Not to mention all the greatest resorts.
CAMANA BAY is a great place for shopping and dining.