They are selling packs of 8 cans (6 cans + 2 FREE) for 99p!
Works out at 12.375p per can!
Just been back into the 99p store in Newcastle-Under-Lyme and they had stacks of cans of 7up Free (sugar free) next to the Tango (also 8 pack for 99p). This should also be nationwide (although stocks at individual stores may vary). Not sure if this applies to regular 7up also at some stores but they only had Diet in Newcastle