How Much Should A Planner Charge?

I have two friends who would like me to arrange a wedding service for them and I would love to do it, but how much should a new wedding planner charge for services and are there any suggestions on how to bill for time spent as they live out of State but want to get married in MA. They are a gay couple and they do have children so money is a concern for them, needless to say! As a good friend and someone wishing to not only do them a favor by making their special day one they will never forget but also wishing to provide me with some income in the process. If anyone has any suggestions for a beginner, please post a reply or even send me an email. I am not a selfish person, but rather want this to be a fair exchange, what would you do out there in e-land if in my/their shoes? They have faith in me and I don`t want to disappoint...

THANKS FOR HELPLING ME!!
Thor in *MASS*