I made a very simple 9 patch, when I made a lap quilt for my grandson out of my husbands shirts and pants. First determine the size, my current lap quilts are 36 x 48 +/- perhaps cut the squares 4". I would guess you would add borders (additional cost) and I added sashing and corners stones around each 9 patch. So you have your time cutting the squares, sewing them together, cost of sashing, borders, batting and backing, then the time to quilt the top. Your time is not free (no matter what a lot of people think) and the cost of fabric today is expensive...I would quote her some where between $200 to $400 and tell her you will keep track of your time and expenses for a final bill. She may be thinking closer to $50, and then it would not be worth your effort. As discussed many times on this board the average person just does not have a clue of the time and materials that go into our craft. In my humble opinion if she really wants it she will be willing to pay for it....