If you're not able to come to terms with normal charges for a quilt you might be better off just quoting her the prices and if she thinks it too expensive she can buy a cheaper one from India or China. By the sound of it, she wants to pay and perhaps you need to overcome your embarrassment at asking for the money. Surely she has asked you to do it because she admires your work. Time and skill are worth paying for. After all, I have seen beautiful Amish quilts on line for over a thousand dollars. The average price just for the materials in my country would be about $350. Custom quilting is sbout $500 on top of that. Edge to edge machine quilting would be about $100 - $150. You just need the confidence to know your work is good enough to ask the correct price.