It turns out that the maximum payment for the highest rank in the highest tier for 75 posts will be 0.00093 BTC, which is ~$36 at the current rate. Not a bad indicator, given that recently many campaigns have paid Hero\Legendary for $30-40, and the minimum payment for a member from tier D will be 0.0002175 BTC, which at the current rate will be ~9$ for 75 posts.

You are wrong to call this campaign the worst paid. The forum has much lower pay per week than 777Coin.