Oil prices in negative numbers for the first time in history will mean super cheap gas soon. ABC’s Alex Stone reports, a year ago Americans were paying a buck more for every gallon of regular unleaded The Energy Department reporting the nationwide average is now at 1.81 a gallon. And prices will likely head way down in the next couple of weeks. The most expensive gas remains in California at 2-70 a gallon on average for regular unleaded. Cheapest gas in San Luis Obispo is at Costco 2.65 a gallon. in Santa Maria you’ll find regular going for 2.59 a gallon at Conserv Fuel and Costco.