David Catron says there is no such thing as a “hospital overcharge”:

Fact # 1: Hospitals do not have separate price lists for patients based on insurance coverage or lack thereof.

Fact # 2: Most hospitals write off about 90% of the charges generated by uninsured patients.

Regarding the first fact, all hospitals bill their patients based on a single “charge master.” When a patient comes in, her account is charged according to the service rendered without regard to insurance. Thus, if an uninsured patient needs an appendectomy, she is charged exactly what she would be charged if she had Medicare, Blue Cross, Aetna, Medicaid, or any combination of these.