"People in much of Minnesota, northwestern Pennsylvania and Tucson, Ariz., are getting the best bargains from the health care law's new insurance marketplaces: premiums half the price or less than what insurers in the country's most expensive places are charging. The 10 regions with the lowest premiums in the nation also include Salt Lake City, all of Hawaii and eastern Tennessee.... The cheapest cost regions tend to have robust competition between hospitals and doctors, allowing insurers to wangle lower rates."