I agree with some of the others. Have her go with you to pick out & pay for all the supplies needed. That way she will know, at least, what the cost for the quilter is. Then you can talk with her about what she feels is a fair price for your time & labor. Please don't cut yourself short on what you are truly worth. The way I charge is the cost of the supplies + half that plus 15%. You need to think of what additional things you will be using that is not in the cost of supplies as electricity, needles etc. I always get at least half down (non refundable) before starting it unless they pay for the supplies. Also have it in a contract stating all you both have agreed to. With them paying part in advance, you have less chance of them backing out after the quilt is finished. I give them an estimated cost of fabric at the high price & let them know if I can catch fabric on sale then I will deduct that from the total price. That seems to please everyone.