I'm taking that too :)
I don't normally pay for MOOCs. Sometimes I do, but it's because I enjoy the program and want to support it, not because I think it will actually get me anything. I know edX has a scheme for some of the courses where you can decide how much to donate (I'll usually leave $10 or $20) and on Coursera they're not terribly expensive. The groups that produce MOOC content do so for free, and if they can't expect some kind of compensation then they're going to stop. And as the upshot, showing universities that this is a potentially profitable venture will encourage the production of more high-quality content.
OTOH, I also have seen edX courses where the fee for the verified certificate is more than the per hour tuition rate at my own college. Let me think, no.