incrediBILL - 5:40 pm on Jul 25, 2010 (gmt 0)

there's no way to tell for certain

Sure there is.

Set up an ad campaign in AdWords that uses a term that will show up in your site and then using a proxy IP address, not your own, click on your own ad and then cancel the ad campaign.

Now wait and see how much you were charged for that click in AdWords :)

It's a lot of work just for a clue and still doesn't give you all the answers you need because different keywords driving traffic to your site, even to the same page, will pay different prices.

Too many variables to figure out, but you can get a basic idea.