As an advertiser, I expect to get value for my advertising dollars.
I guess the question is not how much you should charge, but what value you are prepared
to offer in terms on targeted traffic that converts well.
Rest assured if you can guarantee high quality traffic to your customers you will be able to charge pretty much any amount per click.
Think Google; they can afford to charge up to $90.00 per click on certain keywords because of the quality of the clicks. Contrast that with some so-called "big" networks whose traffic does not convert.