Is it cheap cost per click rates you seek, or most value per dollar of ad spend?
You can purchase a lot of valueless clicks for “cheap” and get nothing of value in return. I suggest that you instead focus on getting the most value from your limited budget rather than simply getting the lowest value clicks that can be purchased.
When managing campaigns we always look at the “value per click” and compare that to the “cost per click”, and the “number of clicks” attainable to determine the value of a keyword.
(VPC – CPC ) * Clicks = Profit
With AdWords, you set the maximum amount you are willing to pay per click. Using the above formula, applied to your bid, will help you to achieve the greatest value per dollar of ad spend.