Baking soda is a good idea.
More generally, it's surprising how many products we buy (including toothpaste, also including many fancy moisturizers and facial products, plus household cleansers, etc.) can be replaced by simple, cheap products we already have around the house - like baking soda, a touch of Vaseline or cold cream for cleaning/moisturizing, white vinegar for cleaning the sinks, etc.)
I bet a lot of these whitening products are really no better than baking soda used regularly, as a good example. My dentist also told me that a gargle with salt water is just as good as using Listerine.
