How much should I charge for drywalling?

Question:My sister asked me if I would drywall a room in her house for her and she wants me to name a price. I told her I would, but I have no idea how much to charge her for the job. All the materials (sheetrock, joint compound, screws, etc) will be provided by her. She just needs to know what I want for doing it. The room is approximately 14'x20'x9'. I have to tear down the old walls and ceiling, hang sheetrock on the walls and ceiling, and replace a light fixture in the ceiling. I have no idea how long a job like this will take and I don't want to ask too little or too much. So any ideas for what I should charge?

Answers:
As labor prices vary from place to place, it is best to call a professional and ask what they charge; then, as it seems you are not a pro you should charge 1/2 of their hourly rate because it will be a learning process for you. I hope you realize how heavy drywall sheets are. You will probable need another person (at least) especially for the ceiling. There are also special tools will you will probably want to rent for the finishing part. You shold just pass that cost on as well.