See http://www.sodastreamusa.com/.

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?

It's not really a warranty issue, it just doesn't work to add the flavor first - trying to pressure carbonate with flavor already added causes extreme rapid expansion (think shaking up a can and opening it). It's not a problem though - adding the flavor afterwards works fine, and you don't have to add their crap, you can add your own after and it works fine.

But, the obvious alternative is to buy a seltzer bottle such as this,

http://www.creamright.com/product/SODA-MO-100-BA.html for $40.

I know from experience that you can add flavor before carbonation. And, the CO2 cartridges here

http://www.creamright.com/product/SODA-110-KAY.html

cost $0.40 per liter of soda.

Peter wrote:

It's not really a warranty issue, it just doesn't work to add the flavor first - trying to pressure carbonate with flavor already added causes extreme rapid expansion (think shaking up a can and opening it). It's not a problem though - adding the flavor afterwards works fine, and you don't have to add their crap, you can add your own after and it works fine.