According to my first search result [1], average CPC is 2.04$ with 1.16% CTR. Say you see 200 pages a day, 2 ads each. You end up at 9.5$/day.
(It's a lot like the creative accounting around media piracy, actually. Assuming that 100% of people who pay $0 for a torrented movie would have paid $10 instead is absolutely deranged.)