you have to determine who and where your market is. in a high-end area? in a real store? craft market? yuppies? professionals? what is the competition in that area? are you selling in person or on-line? will you charge the same amount for simple quilts as for feathered stars (for example)? will you quilt on speculation or on commission? what if someone wants something special that doesn't fall within your pricing range? smaller pieces or different quilting or different fabrics or batting?
how much does it cost in materials alone (fabrics, thread, batting, etc.) to make a king quilt? add your time at minimum wage.
that's rock bottom. that's without any profit. you're not making any money at $550.00. are you sewing for income or love?