You can find blueberry juice in the dieteticas. You can find frozen raspberries / strawberries / blueberries at Jumbo. You also may consider replacing these with more local alternatives -- ie I think it's about now when all the caqui (persimmons) start appearing at the verdulerias. You can make great smoothies with them. There are pomegranites around depending on the season, mangoes and papayas, kiwis, and of course palta and maracuya. There are plenty of other high antioxident fruits that actually are in season other than berries. The little oranges (not clementines but can't remember what they are called off hand) pack a punch. Getting raspberries/blackberries in the dead of winter are a huge guilty pleasure, but weigh more heavily on the guilty side of things -- the ridiculousness of the carbon footprint and the sheer notion of eating fresh summer fruits in the dead of winter is all a bit odd. Frozen is a different matter, they were picked at peak of season (in theory at least).
Other antioxidents easy to find are seeds, chia, sesame, lino etc, they are in every dietetica and supermarket