Toys R Us has their own battery brand on sale AND BOGO, and you can pick up in the store for free!
You have the following to choose from at this stock up price.
2 packages of 20-Pack AA = 40 Batteries $6.99
2 packages of 20-Pack AAA = 40 Batteries $6.99
2 packages of 6-Pack C = 12 Batteries $6.99
2 packages of 6-Pack D = 12 Batteries $6.99
2 packages of 2-Pack 9V = 4 Batteries $4.99
Go Here and make sure you add two packages to the cart to get one free. Or add multiples of 2 packages to get half of them free.