When you figure the time and money required to shop in person, prices at Amazon are EXTREMELY competitive, but what cinches the deal is their customer service.
When I ordered disposable bakeware, they shipped a package of 2 instead of 4 packages of 2. When I asked for the rest, they sent me a full refund. When I ordered 20 pounds of Basmati rice at an exceptional price, and got 10 pounds, they gave me a choice of getting a second 10-pound bag, or a 50% refund.
Anybody can make a mistake, including Amazon, but Amazon is quick to make it right, no quibbling, often giving the customer more than he asked for. I wish Amazon were running for President!