Pickle crisp from your local grocery store is calcium. So is dow flake or pedalow road salt. Magnesium is basically epsom salt. Alkalinity is baking soda. If you want sodium carbonate instead of baking soda for alkalinity, you can buy a 20lb bag at a pool shop for $25. Thats all just if you want to keep dosing.
Ill be getting a ca reactor for my tank soon. Its only a 75g but i like the fact that it is more hands free and also adds trace elements to the tank in addition to calcium and alkalinity.