WASHINGTON—Stuart Steinfeld used to go to two stores to do his grocery shopping every week. These days, he shops at five markets weekly to optimize the lowest prices for the eggs, yogurt, cranberry juice and other foods that he and his wife like to eat.
“I just don’t like spending 30% more on groceries than I used to. It bugs me,” said Mr. Steinfeld, who retired from the financial industry and lives in Santa Clara, Calif.
