I run a sports blog network, and advertising for March is now on sale. It includes 11 blogs that have over 100k uniques per month. Some of the blogs are: http://sportsagentblog.com http://juicedsportsblog.com http://gridirongoddess.net http://sportsbusinessdigest.com http://therealests.blogspot.com http://soccer-source.blogspot.com Sales price is going to be per month based on around a $1.5 CPM scale. PM me if you're interested.
How are you selling it? Full banner space by the thousand? Or are you looking for one person to take the lot?
Most of the sites are only selling sidebar ads, but some of them are doing banners as well. I'm selling them on a monthly basis. You can buy space on just one site or on multiple sites and get a little bit of a discount for multiple sites.