Signature campaign only earn around $300/month, I don't know the specific number you earn, but I don't believe if you have earn so much money, you're really want to get the $300/month since you're always got $1200/month as a stable income.
Here I think you are wrong, my friend, as I earn a lot more than $1200 a month and I am in a signature campaigns earning $400 a month. Everything adds up, and even more if it means charging for an activity such as contributing to forums that I did for free for a long time. It is not an extra effort for me.