You people who get under $0,5 ppc should really try optimizing your content!
Stuff in more keywords, use more h1, h2, strong, italics etc on the highest paying keywords in your text.
Try using meta tags too. Trying is always worth it, won't take much time.
If you can't get your ppc up anyway I think you are in the wrong niches.
If you're doing profit, sure it's good, but if you can make 3x more profit from just finding other niches or optimizing your content and still spending the same amount of time, that's hell alot better!