The Bureau of Labor Statistics (BLS) regularly publishes extensive data. Among the data available is the retail price of milk. For June 2010 the BLS lists the retail price in the average U.S. city as $3.30 per gallon for whole milk.
The Australian Bureau of Agricultural and Resource Economics (ABARE)publishes extensive dairy data. ABARE lists the retail price for a gallon of milk (converted from liters to U.S. gallons) in Australia for June 2010 as $6.92.
The point is there is no relationship between farm milk price and the price consumers pay.