Your maximum CPC is a lot like a bid at an auction. It represents the highest amount that you’re willing to pay for a click on your ad. The maximum CPC helps determine whether your ad appears above or below other advertisers’ ads.

TheDowser Niche Database offers Max. CPC data at the $0.10, $90 & Google Adwords suggested price points.

Further Information
However, Ad Rank is based on more than just the maximum CPC. To ensure that users find useful information on Google and Google’s partner sites, ads are also rewarded for being relevant. The higher an ad’s Quality Score, the more relevant it is. Your keyword-targeted ad’s position on search and content results pages is determined by your maximum CPC multiplied by the matched keyword’s Quality Score. The higher your ad on the search results page, the more likely it is to receive clicks.

The most important factor in setting your maximum CPC is understanding how much a visitor to your website is worth. In other words, what is the likelihood someone who clicks on your ad will purchase your product or use your services? You may not need to have your ad in the number one position if you find that you get a better return on your investment with a lower CPC.