I would start by taking them on a trip to a LQ shop and let them pick out the pattern and fabrics then yes charge them the 400 - 500 for making the top, but tell them they will then send the top off to be quilted by a LA and they will also have to pay for the batting and backing then, make sure they get enough fabric for the binding, .10 an inch is a steal! (ladies around here are charging .17 - .23 an inch) and you will be happy to trim the quilt out and sew the binding on for them. this way they have a part in there quilts and realize some of the time and investment they are putting into the end quilt.