Have your own research here on high price keywords.. https://adwords.google.com/select/KeywordToolExternal
Use the tool suggested above by justkidding and lifeplaye to get estimates. Don't take that data as very accurate. Use it to et estimates.
Here you can get the list of it highpayinggooglekeywords com or you can search as per you keyword in keywordcountry com
just use adwords try and try, and get some target keywords, then search these words via google, if there are many ads, i think the words are good for you.
I used keyword heaven.com, but you can use Market Samauri for free. I would save that anything in the insurance, financial, medical, and law ( dui) will get really high prices.
google keyword tool, But you should also think of issues people are interesting reading about and there is a good chance that you can attract many advertisers. Good luck
Google is your friend. there are many ! http://www.google.lk/search?hl=en&q=high+paying+keywords&btnG=Google+Search&meta=&aq=f&oq=
see my site (under the signature) as an example, one lucky day, i got 6$ per only one click good luck.
i would like to tell you... try your mind.. create a site in a niche...which peoples need to see.if you create a site which have a lot of relevant sites.. first it wil be hard to beat them in competition..second you wil not get success as you can find in a niche.. where competition is lower..