I've just broken the £7 barrier:
1 x 7 inch tomato and herb meatball sub
1 x Moma strawberry and banana muesli thing
1 x green Naked smoothie
= £7.05 for £3.29. Amazing value.
Also: these new 7 inch subs they're doing are really good. I'd say the meatball one is amongst the best pre-packaged shop-bought sandwiches out there.