The California plan, which is one of the nation’s largest buyers of health care benefits, is “viewed as a bellwether of what other large employers will do,” Mr. Robinson said. He and colleagues calculated the savings from the program for the first two years at $5.5 million.

While relatively few companies fully embrace the strategy now, more employers are experimenting with it. Using a technique called “reference pricing,” the employer sets a cap, based on what can be an average price for the service or a price that allows employees to select from a wide group of hospitals or doctors but still excludes the very high-priced providers. The idea is to exert pressure on prices for certain procedures without limiting the individual’s choice of hospital or doctor for all kinds of care.

“There will be acute interest and focus on prices and price variation,” said Ron Fontanetta, a benefits consultant at Towers Watson, who said that programs like this represented one approach. About 15 percent of large employers say they expect to try the technique next year, compared with just 5 percent this year, according to a 2013 survey by the firm.

“This seems something that’s a no-brainer,” said Steve Wojcik, a vice president for public policy at the National Business Group on Health, which represents employers offering health benefits to their workers. “Why pay more if you can get it for less?”

Last year, WellPoint worked with the Kroger Company, a large grocery chain, to start a similar program in which payments for certain M.R.I.’s and CT scans were capped at around $800, and employees were given a list of places that would charge that amount or less.

Kroger picked services that had a significant variation in price but did not vary in quality from provider to provider, according to Theresa Monti, a benefits executive at Kroger. The company also chose to set the price the plan would pay at a point where employees would still have a wide range of choices, she said.

Historically, information about how much a doctor or hospital will charge before a patient gets a test and treatment has been difficult — if not impossible — to obtain, and the federal government’s recent decision to publish Medicare data on hospital charges has focused attention on the wide variation that exists throughout the country.