With Google AdWords you create your own ads, choose keywords to help us match your ads to your audience and pay only when someone clicks on them.

How much does AdWords cost?
In the Google AdWords program, the cost of your campaigns really depends on you -- how much you are willing to pay and how well you know your audience. It all boils down to knowing your own goals and letting us know what they are.
There is a nominal, one-time activation fee for Google AdWords. After that, you pay only for clicks on your AdWords ads, and you can control that by telling us how much you are willing to pay per click and per day.
For example, a new advertiser paying in USD can activate his/her AdWords account with just US$5.00, and can then choose a maximum cost-per-click (CPC) from US$0.05 - US$100. Daily budgets start as low as 5 cents up to whatever limit he or she is comfortable spending.