selling adds on mainstream sites
 

I'm planning to start getting into mainstream in the next year. While I have a lot of experience in adult, I'm limited to what adds sell for on the mainstream side of things.

Lets say I'm looking at a video gaming related website, that has roughly 10k day unique traffic. Site also has a very active forum with several hundred thousand posts (over 300k). The forums tend to have about 500 to 700 active members in the forums at peak times during the day. (about 5k active forum members)

I'm wondering if anyone has idea on what banner/add spots could go for on a site like this? I'm trying to figure out potential add income on a site I'm looking at buying. Anyone have a clue?