I remember there was one forum last year that was launched which makes a lot of noise here because of the huge amount being offered to promote them through signature campaigns here. Sadly though, it was ruined by managers who took off with the money because it was not escrowed properly and the forum owner shell out more funds just to pay everyone else. So I would agree about the suggestions to escrow the price money first.
It was icoforums I remember. The admin did paid a lot of ETH. Sadly they are gone. I really did not understand anything. They really had mismanagement.
I am here in the same page like TryNinja. It's really hard to believe people without reputation. So if OP really wants to run a fair campaign then he needs to user trusted forum escrow. The response will be phenomenon I hope.