I worked with a professor who got together with a few others and created their own digital course content.
This was an interactive package of notes/exercises/self-marking quizzes on the course content.
They sold it for about a quarter of the cost over the previous textbook for the course, and divvied up the proceeds at the end of each year.
I asked about the legality/morality of it, and he replied with 'it's better content, we charge much less, and turn a blind eye to sharing'.
His attitude could be boiled down to : the publishers are the ones making all the money, so I'm going to go direct and cut them out, plus endeavour to bring the content directly to the students.
It wasn't an online solution because the university had some (outdated if you ask me) prohibition on online only content, in case there were students who spent periods where they didn't have access to an internet connection. (note, this was a while ago)
The guy was already independently rich from his side-business of consulting in his industry, so I tended to believe him that he wasn't really in it for the money, though he did want it to be at least revenue positive.
The whole area is ripe for disruption, but then education itself is fat target.