Cheaper PPC alternatives to Adwords

I’m spending a fortune on Adwords so am looking for an alternative that I will be able to get much cheaper keywords but still quality traffic.
I have tried Adbrite which is much cheaper but just does not convert and also Adengage. Both of these are cheap but neither really drive any decent traffic.
Anyone had any luck advertising with Bidvertiser or anyone else?

See original post by mrsexgod