you mean like that "yogurt maker" my mom bought in the late 70's right before I was born? It lived under the counter but I never saw it operated once during my entire life.
Thats a good point. I could see that happening. Another thought I had was the cost - while you do save money over buying soda bottles at full retail price, its not really that much. Doing the math out, between the CO2 and the Syrups, it would cost $0.75 to $0.80 a liter. That is not really much in savings. When I do by bottled soda, I get the 2-liters for about $1.00 to $1.25 on sale which is actually cheaper.
Most of the time I drink fountain sodas from convenience stores. The 32-ouncer (about 1-liter) that I get just about every day costs $0.84 (after tax). So in that case, making the soda myself (and having to bring it with me, and not having ice from a fountain soda machine) would only save me like 10 cents a day. hmmmm.