If you want to get an ankle MRI at one doctor's office in downtown Washington, the procedure will run you $400. Head about two miles Northwest to another's doctor office, and the price more than quadruples to $1,861. Head out to the Virginia suburbs and the price jumps another $300. This would reflect the kind of price variation that we see in other markets," says John Driscoll, president of Castlight Health, which created the map above. "I know we've definitely seen worse than this in a way that's really out of control." Castlight is a relatively new company that works in the business of health price transparency. They sell software to employers, whose workers can then compare the costs of various health-care providers.