I’m sure you could hop on alibaba and find something, or at least the planetary gearbox, probably for $5. Pair it with a gimbal motor for $15 bucks (5 on aliexpress, but those are random motors, however they are similar enough it’s reasonable to change a cad file to match them as needed). Then I would print the casing with CF reinforced Petg or something (higher heat resistance). Probably adapting the interface to the gearbox would be the hardest part. And the output of the gearbox to your application.
But sure if you can get these it looks good for some stuff, until you can’t. I just generally object to the pattern that I often see in hobby communities of grabbing consumer stuff. When it’s just individuals, you really have no choice. but with a community, and the prototyping for electronics boards and even limited mechanical stuff (3d printing and a good selection of parts), we have options, now. We don’t need those nasty polluting people that keep designing things to break, or not as much anyway.
To be fair there are a few cases of repurposing that went fairly well and you can get a pretty good price point esp for used items if there are a lot kicking around on the used market. Still I dislike the casino roller coaster nature of the whole thing. The really good stuff comes from patient construction of good stuff, like simplefoc and hopefully the boards for it that are in the works.
Exploring the idea of a printable harmonic gear might be legit. Perhaps with very fine layer heights to get a smooth surface (I am doing a part with 80 micron layer height right now and have done 50), adequate lubrication and cf reinforced filament it would be practical to concoct a good actuator starting with a gimbal motor. I’m not the person to do that though because I don’t know anything about these actuators, I have become something of an expert on cheaply printing relatively good mechanical parts though.