Do you have a Staples office supply store in your area? If so, get on their email list. A couple of times a year, they run a deal where you buy Duracell AA and AAA batteries, and get all of your money back in Staples "rewards", which is a coupon you can use like money at Staples. I haven't actually paid anything for those sizes in several years.
Of course, you won't want to deal with Staples if you're an 0bama supporter- its one of those evil Bain Capital outfits, dontcha know. . .