You are an artist and should charge accordingly. The 3X's cost of the materials is a good rule of thumb. Then adding for the complexity of the pattern and quilting design chosen will give you a fair market price for you labor. I suggest your friend accompany you in the fabric choices. This way she can't say she doesn't like the colors and you can give your opinion should you see a potential problem with a color choice. Lastly, I would require a deposit that covers the outlay of money for supplies and labor for cuttting just incase she cancels the quilt. This way you've covered your time and outlay so you're only out a quilt to make. Good Luck with your project, I'd love to see the finished quilt before you deliver it.