traffic estimator tool accuracy

On my google reports, for the search term 'sage line 100' in the UK, it says this month we offer a max CPC of £1, and our ave cost per click is 82p, with an average position of 7. However, if I put in these specifications into google's traffic estimator tool, it says that for a max CPC of £1 on a UK search I should be paying 48p per click and should have an average position of 2.8. I'm trying to use this tool to help re-evaluate my PPC campaign, but is it at all accurate? It is doing this a lot. We are currently bidding £1 fo search term [navision], and our ave position is shown as 11.4, but on the traffic estimator it reckons to get first position we only need bid £0.04 - I'm fairly new to all this am I missing something silly?!

Thanks

Use the estimator tool to judge traffic/pricing/position for various search terms relative to one another, not in absolute terms.

Experiment with maximum bid and the consistency of the ad's wording with your site and keyword/phrase.

raz