The difference between selling your own ads and using a network is the middleman. Google takes a cut, so you potentially end up with less. If the paid time tha

The difference between selling your own ads and using a network is the middleman. Google takes a cut, so you potentially end up with less. If the paid time that would be lost while selling ad space outweighs the cut Google takes, it might not make sense. I suppose there's also the possibility of hiring a firm that deals with that kind of thing, but I don't know anything about that. It's probably not cost-efficient if your startup isn't big enough.