I pay £1 for 10 AA Duracell pro cell or £1 for 15 AAA pro cell from my local cardiology unit when i'm in there, they use them in there 24hr heart monitors and have to be changed every time unit goes out, so the battery's are virtually unused , last time i got 60AAA's for £2 because she didn't fancy counting them and just put handfuls in lol, plus the moneys goes into the cardiology units kitty.