Autozone is having a sale on Mobil 1 fully synthetic oil or high mileage synthetic oil with mobile 1 filter for $29.99. There is currently a $17 rebate from when you purchase 5 quarts either in a jub or single quarts and a Mobil 1 extended performance filter.
I think this is a great deal for 5 quarts with a filter for around $13 after rebate.
Also available is a $5 rebate from AutoZone with the purchase of this deal and an STP premium air filter.
There are also lots of retailers not listed on the rebate site, Autozone has worked in the past.