As logoi mentioned, clicks can bring in as little as $0.05. I use the free Google Keyword Tool to evaluate my options for keywords. You can type in a keyword phrase and it will give you recommendations on similar keyword phrases. From here, it will rank them by number of monthly search, competition, and you can also include the average click $$ amount. I generally look for 5,000+ monthly searches, low competition levels, and $$ click amounts of $0.50 or higher.
So by asking, "..how many clicks..".. It really is your best option to pick your keywords carefully and aim for ones that pay a bit higher.