The product not existing isn't a result of there not being a demand or a drive for such a thing to exist. The problem with the textbook industry is that we have professors getting kickbacks from the book publishers, and the students are stuck with the inflated bill as a result. Given the choice, any student would obviously pick an open source textbook over one they have to pay $150 for. The plethora of open source software is proof that we aren't in a shortage of people willing to donate their time to open source projects, supporting the freedom of information.
Maybe if the students had a say in the textbooks that they were being taught with, we wouldn't have the duopoly that is currently being abused by professors and textbook publishers.