I'm typically going around .90-1.10 with adsense. A good friend though, who does pharmacy MFA sites(using PeakClick quality feed, not adsense or the default peakclick feed) is currently swinging around $4.55 a click for tramadol. Luck arse, not inside of US jurisdiction.
Good googly moogly somebody must be desperate for some traffic. They could be getting 100 clicks per day and it would be costing the $500 per day.
A couple years ago I had a web hosting info site I threw up in like 2 hours of boredom, one of the clicks it got was for $19.55.
Supply and demand. That has to be it. $20 for one click. Just 10 clicks like that a day and I would quit my job.
I am still working on it. So far I got 3 clicks that were just over $1 and some that were only $.13. I know there are clicks in my niche that will pay $3-4 because the competition is so tough.