Just to followup for anyone coming across this thread, we ended up buying a used Phillips Travel Charger for my dad’s Oticon MiniRITE-Rs. It was about $140 on eBay from a seller that had a number of them. It works great, he can get about a week worth of nightly charges from it.
Even at that price, it’s an awful lot for an inductive charger not much different than what’s included free with many earbuds, but the fact that Demant gets almost twice as much for the ‘premium’ Oticon branded charger as a functionally identical new Phillips-branded model is disgusting. It makes Apple’s $79 for a replacement AirPods charger look like a bargain! Attempting to abuse customers with an artificially captive market like this is a good way to lose them; Dad will certainly be checking out the Costco alternatives next time he replaces them.