i know asda & marks do a blueberry juice drink, other than that if you are lucky enought to live somewhere where there is a juice bar you could check those out. or buy fresh blueberrys and juice them youself. (i do this quite a lot blueberry and raspberrys through the juicer dash of fresh lime, water and ice cubes)
the cheapest and easiest way to get blueberry juice is to make it yourself. this is how i make my own. i make ice cubes from apple juice (i always have made). put cubes in blender together with fresh berries, or frozen and blend untill liquify. when you pour in your glass add a squeeze of lemon juice. you end up with the most delicious, satisifying and refreshing drink, not forgetting nutritious. i make this with all kinds of berries, melons and very ripe mangoes.