Well as many of us have found out PPC these days is a touchy situation. There is a lot of click fraud going on – do a search for PPC click fraud and you’ll discover what Im talking about.
Personally I didnt get into PPC until early this year, so I dont know who is are was best. Several people have said they have obtained players via goclick, 7search, pageseeker – genieknows is another.
I would suggest that you set up unique tracking codes so that you can assess the quality of the hits youre getting.
Good luck.