Coke Diet/Diet Cherry & Regular 8 x 330 cans on offer at 2 packs for £4 instore at Morrisons, normal price £3.29 each.
Coke Diet/ Caffeine Free & Regular 10 x 330 cans on offer at 2 packs for £5 instore & online at Sainsbury's, normally £3.65 each.
(Direct link: http://www.sainsburys.co.uk/groceries/index.jsp?bmUID=1254130499287).
As a comparison, the 8 packs are 2 for £6 in Asda, 10 packs 2 for £6 in Tesco, so Morrisons/Sainsbury's are better deals than both of them. It works out at 25p per can, the same price as the hot deal for 10pks in Iceland posted a couple of weeks ago.