Purchase 5 participating items, get a $5 rebate. Products included: Vlasic, Open Pit, Armour, Duncan Hines, Log Cabin, Mrs. Buttersworth. Rebate form HERE. Stack a sale with coupons with this rebate and end up with a money maker.
Duncan Hines cake mix is $1 at Target. There's a $0.50 Target printable coupon HERE (you can print 2 per computer) and there are frequent coupons in the paper inserts.