Online learning platforms vary widely in cost depending on the learning needs of their audience, from free to several hundred dollars a month.
For example, the Khan Academy offers free K-12 courses in math and sciences because they are primarily funded by large corporate donations.
But for students who want to obtain an online degree that's accreditated they'll likely have to pay top dollar — for example, a year-long post graduate degree in cloud computing from Caltech delivered by Simplilearn costs $5,000.