The average price of retail gasoline in Wyoming increased last week by 1.2 cents per gallon. says  Prices on Sunday were  12.8 cents per gallon higher than the same day a year ago and 20.8 cents a gallon lower than a month ago. The lowest gas price in the state was found in Cheyenne at $2.61 a gallon. The highest price in Wyoming was $3.39 a gallon.