You’ve probably been looking at my website?
I added this capability recently at the request of a valued friend who asked for it since he, like yourself, was getting creaky in the knees, and in fact could find nothing suitable locally so he built his own.
The problem seems to be with sourcing suitable 12VDC gearmotors that are not hideously expensive, since any cost there is immediately multiplied by 4. He eventually imported something which didn’t work out that much cheaper once he paid the import and the carriage costs.
From the research I’ve done on the subject I can tell you that it’s possible for the averagely skilled workman to motorise his own steadies but it will cost between R30,000 and R35,000. using locally available motors. That includes the remote control electronics.
I’ve taken this as far as the proving stage but I don’t plan to get into the manufacturing business, but I can certainly advise you on what we’ve learned about the process so far.
If you want to ask some more questions, this forum would be a good place to answer them. Otherwise if you want to do it privately you can find my email address on my website.