By your logic, no one can ever estimate the cost of anything. You can't tell me $500,000 is too much for a Toyota unless you've run the company.
It cost Coursera $15,000 - 30,000 to design a MOOC (one time cost). That's less than a dollar per student (for a single schedule, and they have them on a loop!) for most of the classes. Everyone here has IT experience enough to know that the bandwidth and server resources is also inconsequential per student.
Or, do you think Coursera is eating $2B in expenses over and over, with their more than 2M students digging into the free courses? Coursera is a for-profit company, by the way started with only $16M in capital.
Newsflash: Coursera announces their future business model... http://gigaom.com/2013/01/08/with-verified-certificates-coursera-offers-model-for-making-money-from-web-classes/... is to charge $30 to $100 for courses. Now... that including a profit.... am I the stupid uninformed one for guessing their cost are no more than $20?