Absolutely show her the price breakdown BEFORE you start. Most people have no idea what the cost is. I sell both in a store and online. The two standard ways to price are 3 x's the product cost or the products cost + hourly cost (these also need to be adjusted for what the market will spend). My suggestion is you take her with you to purchase the fabric. She pays for it and then pays you for your labor. I try to never spend more than $3 per yard in order to recoup my costs. But, I spend a lot of time getting these fabrics (downtown fabric marts, online, huge sales, etc) because I do it as a business. Show her the fabric requirements for the fabric, give her an approximate time (if she doesn't know quilting, break it down - cutting, sewing etc.). The point is to educate her in what goes into making a quilt or even a quilt top BEFORE she commits to it. Many, many, many of us have been burned by folks thinking it was a simple, quick and inexpensive thing to throw a quilt together. And, as hard as it may seem, try to keep it fun, nothing worse than working on a project that has stopped being fun!