Using the Google Adwords Tool, I'm assuming any keywords that have high competition will have good CPC. Decent keywords I'm familiar with would be Web Hosting and other random things to do with money and loans.
God, if we knew high paying keywords, why on earth would we tell you...?, can you illustrate me please...
I think the idea is simple: keep getting content related to health, beauty, law etc and you will get high paying clicks as well. I get from $0.10 to $2.5 on the same blog, same niche, same keywords..
$3.99 is nothing. If you find a niche with high CPC you can earn 20,00 € per click. really. It happens to me
The highest click price I ever got was something around 6$. But I suppose it could really get up to 10$. However you probably wont get too much traffic on those (special finance?) topics..