Good day, Lodestar.
I'm currently using an inexpensive, organic soap as a toothpaste. It's called Dr. Bronner's.
It's widely available in health food stores -
at least in the USA.
Dr. Bronner's Magic Soaps Retail Store: Peppermint Liquid Soap - 4 oz.
The liquid soap is very gentle, non-abrasive, and a little bit goes a long way. Therefore, it's very economical.
BTW, I should mention that it's obviously fluoride-free.
I believe other board members may also be using the same "toothpaste". Perhaps they can chime in with their experiences as well.