I just get a shed load of AA batteries once every so often from CPC - last ones were Energizers @ £6.27 for 24
http://cpc.farnell.com/energizer/special-pack-12-12/battery-aa-classic-12-12pk-energizer/dp/BT03685
http://cpc.farnell.com/energizer/special-pack-12-12/battery-aa-classic-12-12pk-energizer/dp/BT03685