I wouldn't sell a king size quilt for less than $2000.00, especially if it was labor intensive. I would imagine you paid a lot more than $200 for the quilting.
Figure out the yardage (front and back), times $11.00 per yard. What did your batting cost you? What was the cost of the quilting? Calculate the cost of thread, needles, shopping for the fabric, and prepping the fabric. Then take into account the number of hours you spent cutting, piecing, etc., take that times a minimum of $10.00 per hour. (and that would be dirt cheap labor!). Add it all together, the add a couple hundred dollars for the items you forgot about. Will you ever make another one? Do you really want to part with this one?