I first heard about this when Sean Hannity advertised it on his radio show.
According to http://www.sodastreamusa.com/Sodamix-Flavors-C12.aspx
, enough root beer flavoring for 12 liters costs $4.99 ($0.83 per two liters).
According to http://www.sodastreamusa.com/60L-Carbonators-C38.aspx
enough CO2 for 120 liters cost $29.99 ($0.50 per two liters).
So, excluding the startup cost, this soda costs $1.33 per 2 liters. Where I live, I can usually buy big brand names such as Mug and A&W on sale for $1 per two liter bottle. Store brands such as Big K cost around $0.75 per 2 liters. Seems to me that SodaStream is marketing to suckers.
But, if you add your own Root beer flavoring, the cost can drop to almost $0.50 per 2 liters. In the video, flavoring is added after carbination. Does anyone know whether flavoring can be added before carbonation without voiding the warranty?