reference request - How much does it cost to make a MOOC universally accessible, as defined by the Americans With Disabilities Act of 1990?

Is there any research/study/survey that tried to quantify the cost of making a MOOC universally accessible, as defined by the Americans With Disabilities Act of 1990 (mirror)?

I am aware that the cost depends on several factors, such as the type of content the MOOC contains ( video / text / etc.).

The question is motivated by the lawsuits some educational firms received / feared to receive to due to lack of accessibility of the course materials: