I can only offer an emphatic YES. I think that there are enough geeks out there that would like to see this monopoly broken that I predict a Kickstarter would be a rousing success.
Even if you build a decent clone, it will be hard to break the monopoly due to one key feature: reliable factory reset. Teachers will require a device that can be reliably reset of all user data to prevent cheating. If the student can hide or mask the factory reset, it will never be approved for testing, and thus will never be approved for classroom use.
I think I would explain that it's a placebo and instead suggest verbally banning students from using their calculators for evil, then discipline them when they do so.
It won't be for a while (KnightOS can't even do math right now, but it is a passable unix system), but I will continue the research and perhaps work towards that goal. The biggest concern I have is that I am only an amateur EE and I don't know if I could take people's money for something I may not succeed at.