How much would it cost to order these chemicals? Where could I order them?

Sorry, individuals can't order chemicals from suppliers, they sell to legitimate organizations only. However, you can get calcium chloride in a hardware store, as it is used as an ice melter for sidewalks (it's the white round pellets - check the label to be sure). The best place to get sodium carbonate is at a swimming pool supply store. Both these should be pretty cheap. I have no idea where the layperson can get some magnesium bicarbonate; but maybe if there is a college or university nearby, perhaps you can give their chemistry department a call, they might get you a small amount.