Do what you can afford, don't let others try to convince you what is good and what's not. Like anything, moderation is key and if you can find a sports drink w/less sugar and less price then nothing wrong with it. Main thing, hydrate yourself well.
I really hate the taste of coconut water by itself, I prefer to mix w/it something else. I only use it during long or hard workouts--especially in the warm/hot months. Other times, I will drink a sports drink w/little to no sugar. In the winter/cooler months, I drink just water.
As for the person saying toxins, etc, etc...running outside and breathing the air can be toxic. I think if we worry about every aspect of what we eat/drink and breath then we are not truly living, are we?
Listen, when I grew up all we ate was processed, not wholesome foods, and ate out at fast foods a lot and I drank tons of milk/ice cream and yet, I never broke a bone in my body (even to this date--40+years later) and I was VERY active in sports/exercise. I still weight about the same as when I was a young adult and have been healthy ever since.