I tried to get into MP3 and video downloads niche and have some 160 keywords but minimum for every one keyword is minimum $10/click on searches. Any idea how to get Google to lower the cost ;-) On the other hand I get a lot of clicks "on content" and pay 1 cent /click for Immigration to Canada related keywords. Go figure...
mrx is right improve your QS. Do this by theming your ad and and landing page around the keywords you are bidding on. Make sure your theme adgroups around similar keywords also.