Your cost per click is the amount you pay per click to Google. It depends mainly on the level of competition you have in your sector. The more your competitors bid for the same keywords you do, the higher the cost per click your keywords are. Some keywords are more expensive to bid than others, depending on their popularity. If you want advice about your cost per click, or want to lower it or higher it, contact your account manager and he'll be happy to make the changes necessary. Take into account that manual bidding optimization is part of our Premium features. More info about cost-per-click on Google.
How does Google distribute my daily budget?