Check some websites of what the Amish charge for their quilts--some cost more than $1,000. If you're doing everything, including the design, pay yourself fairly. Making a profit off your hobby is nice, but for whatever amount of time you're working on her quilt, that's time away from the ones you want to make, so it's important to pay yourself enough so you don't feel resentful of the time you're devoting to someone else's project.