You could give Valueclick and Casale Media a try. If they accept you they are very good networks. For banner ads their CPM varies, but at the lowest you can expect a minimum average CPM of around $0.20 - $0.30.
The first 2 networks listed here pays me around $0.45 - $0.70 CPM on each banner ad format and I put 3 different ad formats on each page of my entertainment site plus I also chain them so that I earn even more. With 3 banner ads per page I get around $1.35 - $2.10 on every 1,000 pageviews. These are 2 top tier and reputable networks which has got some requirements in place. If you can't get into these then the ones listed further down are much easier to get into, but obviously still would need a few requirements and still pay alright. Good luck with earning from CPM and with your website.