You can easily make your own! Just follow the yogurt making recipe here, then when it is set, add some water to the jar (1/4 cup), shake it up a bunch and there you have it! Yogurt drink that can be poured into a cup or even funneled into one of the plastic containers like the picture above (if you saved some) and reuse them over and over.
Get creative and add some fruit to the yogurt, a bit of liquid and blend it until smooth. I bet they would freeze well too, I have not tried. Frozen yogurt would be a nice treat on a hot summer day!
If you are not up to making your own yogurt, you can still skip buying the yogurt drinks. Purchase a bulk amount of yogurt, preferably a recyclable container over a bag that would be considered waste (black box) and add water as needed for each drink. It would create less waste compared to buying into the pre made yogurt drinks. Buying in bulk is better than buying individual servings!