I have a few sites that are funny. When I only get 100 visitors per day It was making $5 with no problem. Then my site was on the front page of google and got 4k hits a day put the clicks were WAYYY less than when I was getting tiny traffic. Now I'ts not on the first page anymore and the CPC is back to normal. I've had click for $2.70 on my New york site (See sig)