That really is the estimated cost per click for that keyword. Depending upon how closely one adheres to the rules Google has established, depends on what one actually ends up paying. Google rewards those with a cleaner set up with a lower price. The same can be said about ones actual website and how close to the first page your website gets in the organic not paid for search on Google.
You can see from the image I posted though, that $10 is the price google estimates they will charge per click.