one option unless you can find the big bags of rock salt i forget which ones from a home improvement store and a big bag of baking soda from costco or sams club (if i remember correctly you have to bake the baking soda to get the co2 out)
I bake my two part. Randys recipe with calcium chloride from bjs in a 5 gallon bucket and baking soda from bjs in the 5lb bag. Its very easy to do and costs almost nothing.