Received from Terry Gray at 6/13/2020 00:17 UTC:
Jim, Sodium Hypophosphite Monohydrate is apparently a controlled substance but for whatever reason it seems to be much easier and far cheaper to obtain than its cousin Calcium Hypophosphite, and I haven't talked to anyone that knows why! I can obtain it from several places in the US as well as from several Chinese vendors on Alibaba for a much lower price than CH.
Perhaps I'm wrong, but I bet you found places that list a price for it, and seem to indicate it's available, but the real hassle will come when you actually try to order it. Established labs/companies with a good reason can get it in limited quantities, but as a home hobbiest (assuming here) it's another story. I truly wish you luck.
Jim H
