Your work is stunning! As a textile artist, you deserve to be compensated well for the work. You already estimated the cost of supplies & approx hours you'll have invested; how much per hour would you expect to be paid at employment in any other field? Doing a commissioned piece is expensive - charge a sufficient price to make it worth your time; otherwise, why do it at all? I could not afford a purchased quilt of this caliber, but clients who ask for a specific piece of art should be willing to pay compensatory prices for the piece created. Offer them a price worthy of your skill.