You can score a 48-count pack of Amazon Basics batteries for as low a s$14.13 on Amazon. You'll get 24 AA and 24 AAA batteries.
This pack is priced at $18.83, but you'll get the deal when you clip the Amazon coupon for 10% off. Then check out with Subscribe & Save for up to 15% off. Your first order will get a minimum discount, and when you have five or more subscriptions shipped to the same address, you'll get the maximum discount.