Cheap CO2 production?

[asdfghjklnyc]

This (http://www.aquariumguys.com/nutrafinco2.html) product says it generates CO2. For about $20, does this really produce a significant amount of CO2?

[Storm Crow]

A milk jug, some yeast and sugar will make CO2 cheaper! You might even add some fruit juice and make jail house booze! lol

[Abattoir Dream]

i think candles make co2 aswell...