Has anyone joined an ad network as an advertiser?

I was wondering if anyone has had experience of promoting their own offer via an ad network. I know there will be plenty of affiliates here but I would like to know the costs and the process involved in joining as an advertiser.

I know networks like commission junction require that you make hundreds of thousands in monthly sales but there must be smaller, more approachable networks.

Thanks

I did not join yet.But I soon I will join bidvertiser as an advertiser.I hope I can promote my site cheaply through their network.