For the third survey in a row Billings is the cheapest place in the U.S. to buy gas. According to the most recent Lundberg Survey the average price for a gallon of regular in Billings is $3.33.  You’ll pay the highest price in Chicago, $4.10, the national average is $3.71. Diesel was also down six cents to $4.07. I was in Spokane for the NCAA basketball tourney and diesel over there was $.22 higher than here in Missoula.