Gas prices are heading back up as more people go back to work. Triple-A Arizona says the average price of gas in the state is up two-cents a gallon this week to $2.19. In Flagstaff, gas is up a cent-and-a-half to $2.33 a gallon. Some stations are selling gas for $2.23 a gallon and lower. In Prescott, prices at the pump are up three-cents a gallon this week to $2.23. Some stations are selling gas in Prescott for $2.09 and lower.