“Caren Gaffney would be the perfect contestant on ‘The Price is Right.’ She moves from store to store, meticulously combing the aisles and taking down prices. A head of Boston butterhead lettuce. A bottle of Advil. Car inspection. Diamond bracelet. Eyeglasses. A 50-foot black TV cable. Washing machine. It’s an eclectic shopping list that comes from her employer, the U.S. government. The items that she prices — and thousands of others — are reflected in the government’s most closely watched inflation barometer. The Consumer Price Index measures the prices shoppers pay for a market basket of goods and services.”