I have to admit, it's very hard to sell me on these (what I refer to as) Snuggy products, but this one actually seems like it'd be a decent investment. If you're going to go out and buy soda, there's no problem going out and buying soda syrup. Plus, like you said, eco-friendly.
So really, this thing actually has a purpose other than "being really lazy."
We actually made root beer in Biology class last tuesday. We got to have it yesterday, it was awesome. Our group got the best grade for it.
It tastes a lot different than the stuff you get in the store, and you can't store it because it'll keep carbonating and eventually the bottle will explode (I laughed at the thought during class).
For the science fair in 7th grade I made cola. Best part of the experiment was when every one of my tests thought that my homemade cola was the store bought stuff. I mean, it was only a model of 5 people, but still, 100% thought it was the real-deal.