Uncle Sam's Eyes in the Aisles

"If it is a seasonal item, most likely it is going to be gone the next time you go there. You got to look all over for it and make sure you got it," Gaffney says.

If the store is out of the item, Gaffney has the tedious and often time-consuming task of finding a substitute product that is as close to the original as possible.

For instance, Gaffney might be forced to find a substitute for a woman's blouse with the following specifications: sleeveless, 85 percent cotton, 15 percent rayon. Made in Malaysia for a national brand. Does it have any special features, such as appliques, embroidery or beadwork? What's the hip length?

Gaffney says she has priced all kinds of goods and services, including a hysterectomy, a cremation, tires, car repairs, expensive jewelry and liquor.

"Beware of sales," Gaffney says. "They say it's a sale, but the sale price is really the regular price."

All of the thousands of prices collected by Gaffney and others pour into the Bureau of Labor Statistics, where they are analyzed by economist Sandra Schneider and her colleagues.

Schneider's area of expertise includes cereal (box, bag, hot or cold), bakery goods (fresh and frozen), and nonalcoholic beverages (juices and soda).

Prices for doughnuts, pies, pastries and other baked goods tend to be pretty stable, while prices for carbonated beverages can fluctuate widely, reflecting the waxing or waning of discounts and promotions, Schneider says.

"This is actually really complicated," says Gollannek, Gaffney's boss. "Everything that makes up the minutiae of your life" as a shopper is something the government's price checkers are keeping tabs on.