if you want to target customers in is buying cycle and not paying too much for clicks check this thread: http://forums.digitalpoint.com/showthread.php?p=11021468#post11021468 it's not always about the price of the traffic, it's about quality
It will be hard to get that advertising at the rate you want. You can try AdBrite thought, you can advrite at $0.03 usually per click or sometimes they have something lower on a specific site.
Here is a list of some of the many PPC providers out there. Tough will have to stick with second tier PPC providers to get traffic at those rates. (I'm not in any way affiliated with neither this site or the sites it links to) http://searchenginewatch.com/2156291 And, should you want a personal recommendation from me (a company that is not in that list but I think that yields good results), PM me.