Thumbler is correct, as the ranking also factors in clickthrough rates. Someone bidding $1/click with a 1% clickthrough rate will likely show up below someone else with a 50 cents/click bid but with a 10% clickthrough rate.
You can see Overture bids at:
http://uv.bidtool.overture.com/d/search/tools/bidtool/
although they can be very different from Google.