I've done several custom quilts (both t-shirts and memorial quilts). For a charge I calculate how much I will need for materials (sashing, borders, backing, binding, battings, interfacing etc) plus $.02 per inch for quilting, for a twin to full size quilt about $150 to $200. I tell them that is the price for materials. I then tell them I also am charging them $250 or up for my time and labor. The labor charge is based on the complexity of the pattern.