Try changing the color schemes of your ads, it can make a huge difference. I test different colour schemes every few days.. an average day hovers around 400 bucks but some days with good color schemes it goes to more than twice that.
There are many factors that could affect the willingness of a visitor to click though, so it's difficult to say without knowing what the site looks like, your niche, where your traffic is sourced from (quality traffic always wins over quantity), if the ads are relevant etc etc.