Just been to asda and they had these on offer.
A funny one, i checked it out and bought two so its correct.
DURACELL 9V 500039403820L
or 2 for £3.00
Was also on offer with Energiser Ultra 9V As well.
Shop assistant said that they where 2 for £2.00 last week. I tried to get them for that price but to no avail!