revenue of each click depends on importance of keyword but also the location of click area. there are many keywords that can give you good income even $15 per click as sports, hosting etc. but it will depend on click location, clicker's browsing and as well as google's hidden criteria
Most high paying keywords are actually general terms that are familiar with a lot of people. On the other hand, if you want a specific keyword, then you might have to work on this for a bit.