Packs of 12 AAA alkaline batteries are 88p in my local Asda in Carlisle. There was no reduced label, they were just alongside the other batteries.
Presumably they're a discontinued pack size - they were next to packs of 16 of the same kind that were priced at £4.60. (16 pack on the Asda website: http://direct.asda.com/ASDA-Long-Life-AAA-Batteries---16-Pack/001134706,default,pd.html
I've bought these before and they're decent batteries.
Presumably this is national in stores that still have stock.