Identical products are often sold at different prices at different times and in different shops. This column uses data from 1,000 products across more than 1,500 stores to argue that, in France at least, consumers are in a relatively good position to decide where to go shopping. Expensive and cheap stores tend to be persistently expensive or cheap over time and across the products they most commonly sell, and the retail chain to which a store belongs is a good indicator of its expensiveness.