If you threw a dart at a dart board, blindfolded, while riding a horse backwards, you will have a 50% chance of being more accurate on the CPC.
It's a number, in my case, when we used to use estibot, it was one of about 100 markers we used to determine if a domain was worth anything. There are some other companies that offer keyword data that are a lot more accurate. But CPC numbers from all of these companies are almost random numbers. That's not what you would get if somebody clicked on the ad. It's what the advertiser who is a brand new advertiser "may" have to pay to be #1. If you have been advertising for a while, the cost is probably about half of that number.
Estibot has it's good parts and bad parts. If you decide to use them, just use them as a information, it's as accurate as they can get. But it doesn't mean that it's real world numbers.
Donny