A team of four researchers looked at medical expenditure bills that represented more than 8,303 emergency room visits. They found, essentially, two things. First, huge variation in prices: Bills sent out for sprained ankles ranged from $4 to $24,110. Second, overall, really high prices: The average emergency room visit now costs 40 percent more than a month's rent. Researchers used data from the Medical Expenditures Panel Survey, which looks at how much American families spend on, well, medical expenditures. They looked just at what they found to be the 10 most common reasons listed for trips to the emergency room—designated by billing codes—and how much each one cost. The figures show a huge amount of variation.