If Walmart or CVS tried charging five times more than local grocers for bread, milk and bananas, their customers would promptly start buying locally. Yet a new report from the Consumers Union shows those same chains get away with pricing prescription drugs several times higher than local pharmacies. Researchers called more than 150 pharmacies in six metro regions for cost quotes on five commonly-prescribed drugs. They found the total cost of these drugs was dramatically lower at independent retailers ($107). Chain drug stores charged an average of $849 for the same five drugs, big-box discounters charged $527, and grocery chain pharmacies charged $565.