to get 2$ per click is very hard.i gues ads that a few people will click on them are the most paying.ads that sell something also
download market samurai software...then do research . ussually the HPK topic a difficult and high competetive topic like loans, mortgage, credit card, college, laptop
Shawn is listening to the Sisters of Mercy! Frick that rocks! [btw, you're in tough to generate significant traffic from $2/click keywords]
There are many high paying keywords even Hosting is $7 but its mean is not regular rate. high paying ads are for high level and google's favorite sites
You could use the Market Samurai software to figure out how much advertisers are paying per click on average for a particular keyword. Just use their Keyword Research tool to find this out.