There are various sites that sell lists of keywords and cost information. The oldest that I'm aware of is TopPayingKeywords.com
They sell a list of over 15,000 keywords/adwords prices sorted by popularity and price for $199.
A newer site that claims to have much better targetting is <snip> They have an even bigger list of keywords/prices for $149, plus other lists dedicated to business terms, financial terms, etc. for $99 each.
[edited by: Jenstar at 4:08 pm (utc) on Feb. 21, 2005] [edit reason] No URLS as per TOS, please! [/edit]
Personally I'd like to know what keywords of my own are pulling more. If I run a fruit site and bananas make more than peaches, then writing more about bananas would make sense. However with a site that has seemingly random keywords on each page, its not that simple ;-)