Somebody said that above $0.50 per click is good enough.This can go with any niche if you get click from the search engines. If you get traffic from search engines, the per click converting is very well even though is not about finance related niche. But with finance related niche you can get perhaps more than $1 per click. Don't start niche about phones model. That is really-really cheap per click if you are doing adsense. But that niche is the easiest thing to blog about.