price should definitly be discussed & agreed upon LONG before even cutting a piece of fabric!
3 x cost of material is a good place to start- you can adjust up or down from there as you see fit.
i charge anywhere from $350-$500 for a basic queen sized quilt- i also supply the materials. and of course it depends on the pattern. but it needs to be figured out before you go any further- she may have no idea what it cost's to have a quilt made---and may change her mind