The SodaStream machines are gaining in popularity due to the economical sense (cheaper to make soda than to buy it), health benefits (add fresh fruit juice instead of corn syrup), and ecological mindedness (no more disposable plastic bottles). And it looks so fun!
You can watch this SodaStream silly demo video on how it works. There are several models to choose from. The "Penguin" shown above (which would look totally cute sitting on your counter) is available as a starter kit which includes the machine, 2 carbonators, 2 glass carafes, and flavor variety pack (OU Kosher!) for $199.