Just keep some frozen berries in your freezer. You probably already have apple juice, orange juice, and a banana or two in your house, right? Who needs Jamba?
Some fave combos:
Oj, ice, fresh strawberries & blackberries
Oj, ice, blackberries, banana, frozen yogurt pop (stolen from daughter's stash)
Equal parts oj & apple juice, frozen strawberries, blueberries, banana
