Oregon gas prices have risen 5.1 cents per gallon in the past week, averaging $3.61 per gallon as of Tuesday, July 6, according to GasBuddyâs daily survey of 1,307 stations in Oregon. Gas prices in Oregon are 23 cents per gallon higher than a month ago and stand $1.05 more per gallon than a year ago. Prices in Hermiston are about $3.47 According to GasBuddy price reports, the cheapest station in Oregon is priced at $3.23 while the most expensive is $4.39, a difference of $1.16. The national average price of gasoline is unchanged in the last week, averaging $3.12. The national average is up 7.9 cents per gallon from a month ago.