Office Depot - 4-pack duracell batteries $1 or less YMMV in store only
Select Office Depot stores have 4-packs of Duracell batteries on clearance for $1. Some stores are as low as 54 cents! Office Depot takes coupons so you could potentially get it for even lower with a coupon.
**In store only!** YMMV. To help find these I put a full store inventory below for each item. You will find the batteries in a display by the cashiers.