Many domainers use the Google keyword tool to get a feel for how much a keyword will pay. Of course there is a lot more that goes on and just because it shows $25 CPC does not mean you will get anywhere close to that.
WordStream did a nice info graphic explaining how things work from the advertiser side.
Nice graphic – Thanks for posting! Very useful for people who manage PPC campaigns.
It’s only a matter of time before another company opens a competing advertising network on a domain like Ads.com that will be much cheaper to do business with. At the moment adwords is expensive and ineffectual for a lot of businesses.