Get Energizer batteries for 11 cents per battery
Check your Walmart stores for specially-marked 8 ct. packages of Energizer batteries and get a $10 Walmart gift card with a mail in rebate when you buy 2 packages. Use two of the $1 printable coupons to pay 57 cents for an 8 ct. package of AA or AAA batteries–7 cents per battery.
You can do this deal 4 times, so you can get 8 packages at this low cost.