LANSING, Mich (WQTX) Motorists are digging a little deeper into their pockets for a gallon of gas this week.  Triple-A Michigan says prices are up 2.7 cents per gallon  over the past week to a statewide average of $2.76.  The auto club says the average is 36.8 cents per gallon higher that at this time last year.  The cheapest price for self-serve regular can be found in the Saginaw/Bay City area at $2.71 a gallon.  The most expensive is in Marquette at $2.84.