[Lorenzo M. Vidali]"I know the market isn't as big as After Effects, but there also isn't as much out there for Motion either."
Ironically, I'd say the exact opposite. For one, Motion templates are fully usable and customizable both with, but just as much without Motion. Namely in Final Cut Pro X. Since near 100% of every title, effect, transition and generator in FCP is in fact a Motion project, yes. A level of usability and flexibility AE templates can't boast. And with that there is, again imho, far MORE out there for Motion that is usable and of any interest to a much wider audience than for AE, especially since the potential audience is exponentially larger than that of AE/PPro. AE's strength is specialty plugins, not so much templates and making effects and transitions is even an option to begin with.
Not much out there? You're familiar with motionVFX.com? FCPXfree.com? FXFactory.com?
Whether there is any demand for your templates and plugins of course hinges solely on their quality and usability. But either way, with AE templates your only real target is AE users, with Motion templates, FX, transitions etc., things that aren't even possible with AE, your primary target is FCP users, but also, to a much smaller degree, Motion users.
Although I gotta say, they're catching up fast. Just check out MotionArray.com's array of Motion Graphics Templates for Premiere. They're made in AE for Premiere, just like Motion & FCPX. Same stuff you see for FCPX for the most part. They aren't as advanced as the whole Motion/FCPX system by any means, but there they are. https://motionarray.com/browse/motion-graphics-templates
I see MotionArray is carrying FCPX templates now too. Something I told him he should do 3 years ago, but he never replied to my email. :P