If you are looking to dip your toes into the world of banner advertising then SiteScout is the place to start. SiteScout is what you would call a self-serve banner network that allows you to set up your own campaigns. You get to choose what sites in their network you want to display your banner on, where you want to display it and how much you are willing to pay per CPM. Because SiteScout buys a lot of remnant and excess impressions at a discount this brings your CPM price down substantially.