Melanie,
You have asked the question every quilter faces. How much is our work worth? If the person really wants a quilt take them to a store to look at fabric so they know how much it costs. Let them see how expensive batting can be and the difference between them. Show them a price list from a long armer if they want it machine quilted and then tell them your construction of the quilt would start at $10 a square foot for basic piecing or simple applique. Don't be afraid to raise the price for more complicated patterns. As a handquilter for hire I charge $10 a square foot for basic quilting and go up by 2 cent inquirements if the qulting gets elaborate. I also charge at my cost if I supply the batting and backing. I also charge an extra $15 if I do the binding. I usually charge what the original price of the backing and batting would be if I was not able to find a bargin or discount.
If the person does not supply the fabric or in my case the backing and batting I get a deposit big enough to cover that expense up front. I usually get a $50 deposit if I am supplying the backing and batting. If they decide they don't want the finished quilt the deposit is none refundable and I keep the quilt.
Just for kicks keep a count of the actual hours you spend making a quilt. It will be an eye opener for you and help you realize how much your time is probably worth.
Good luck