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Ford Patents A Way To Bring Ads Inside Your Car
(insideevs.com)
This is a most excellent place for technology news and articles.
It's not that expensive in the US. A few hundred is typical, and you don't need a lawyer (though spending the money on one up front will save you from spending more when you screw it up the first few times).
Ok, that's less than what I would have expected, but still more than what most people want to invest into something that's basically a joke.
Feasible for a non-profit however
Don't you need working prototype to get a patent? Otherwise musk or bezos or another for-profit asshole could patent every known scifi gimmick, wait until someone actually invents it and then send him a bill...?
Google says no, you don't need one.