8 Pack AAA Rechargeable Batteries (That's 0.50p per a battery for 1200 times use)

£3.99 – Amazon
POWXS AAA Rechargeable Batteries 800mAh 8 pack With Cases Pre-Charged 1.2 Volt Ni-MH AAA Batteries.
POWXS rechargeable AAA batteries up to 1200 cycles, can be recharged up to 1200 times by using any good-quality Ni-MH battery charger, reducing the waste of disposable AAA batteries.