Amazon offers Prime members the Panasonic Eneloop Pro AA Ni-MH Pre-Charged Rechargeable Battery 4-Pack, model no. BK-3HCCA4BA, for $13.32 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $6.01.) That's the lowest total price we could find by $4. The batteries can purportedly be recharged up to 500 times.