You need to research this, come up with the pricing formula that works for you, write up a contract, make sure you and customer agrees to the terms then insist on a 50% deposit before cutting a single piece of fabric.with the understanding the deposit is Not refundable and the balance is due at completion Before she gets the quilt. If you are going to sell your services you need to treat it as a business! I sell baby quilts for $150, queens can cost close to $1,000 . Don't sell your services short. If you are not ready to make the ( jump) into selling be honest and tell her you are not ready to take on such a project. If you want to do this write up your contract, get your deposit ($250-$300 at least if she wants a bed sized quilt). Good luck. Stating she already burned you once I'm surprised you would be considering this.