Cheap PPC source

I have a niche classified ad site. In the area of Golfing. Over the last year it has built itself up slowly, mainly through SEO. I havn’t really gotten incolved with it much. I am getting about a 20-30% increase in new visitors each month.
I am at the point where I am thinking that I may drop a little money on some PPC ads to juice up the traffic a bit. I have been thinking about AdWords, Bidvertize & Adbrite. I would like also to target the US & Canada.
I have also considered purchasing some text link ads of some sort.
Any one out there have any suggestions? I want cheap traffic because this site isn’t earning yet, and well….the economy sucks, so I don’t want to be overly aggressive. Any suggestions would be appreciated.

See original post by stallican