ROANOKE, Va. (WDBJ) – Average gasoline prices in Roanoke have risen 9.9 cents per gallon in the last week, averaging $3.11 per gallon today, according to GasBuddy’s survey of 155 stations in Roanoke. Prices in Roanoke are 26.6 cents per gallon higher than a month ago and stand 10.5 cents per gallon lower than a year ago. The national average price of diesel has risen 6.9 cents in the last week and stands at $3.99 per gallon.