It gets 175 uses before you need a carbonator, and I haven't used mine up yet. I would
recommend purchasing extra bottles. The one I got for Christmas has just one bottle. I typically keep a bottle of chilled tap water (we have great water here) in the fridge, then carbonate when I want to drink it. Would be nice to have some extra bottles as back up.
My friend runs the blog Former Chef and she has a few recipes developed for her soda stream. I've linked to that...see just above your comment.
Personally, I'm thrilled with just the straight bubbles. I'd be a Perrier girl if it wasn't so expensive. This solves that problem.