I wouldn't look at this as binary. You have more options here. You need to target bloggers, who look like they might be up and coming. I'd even target a spec

I wouldn't look at this as binary. You have more options here. You need to target bloggers, who look like they might be up and coming. I'd even target a specific niche. Basically, go to them, and say, "If I can get six of you signed up, I can then get awesome rates from people interested in your niche." Now the hard part: deliver! Once you got all six on board, I'd spend everyday on the phone, e-mail reaching out to the major and minor players about how they've got to advertise with these up and coming trusted players in the niche.