Amazon offers its Amazon Prime members the Sanyo Eneloop Ni-MH Rechargeable AAA Battery 4-Pack, model no. SEC-HR4U4BPN, for $9.87 with free shipping. (Non-members can spend over $25 to qualify for free shipping; otherwise, shipping adds $5.58.) That's the lowest total price we could find by $4. The four 800 mAH AAA batteries are precharged and can be recharged up to 1500 times.

Amazon Prime membership is $79 per year; however, Prime is free for college students for one year, and free for parents and caregivers for three months.