AT least have her buy the pattern, fabric, batting, and thread.
She sounds like a classy lady to insist on paying - but on the other hand, she may not have any idea how much it costs to actually make a quilt.
If I were you, I would start out by giving her an estimate of how much JUST the components of the quilt will cost - and see if she wants to continue. She might have sticker shock when she finds out!