The way this works is: you install a Chrome extension which automatically uploads anything you get from PACER into a free archive.
How are they funded? I expect they're a 501(c)(3). So it's not a question of whether PACER can be free; it already is, partially.
As for patents: Google used to host all the patent files for free, and then someone complained that that gave them an unfair advantage (note: but what???), so now someone else hosts them for free.
So I don't think finding the funding is really much of an issue nowadays.
[1] https://www.courtlistener.com/docket/7185174/united-states-v...