I'm painfully slow to begin with,and end up in pain after just a couple hours in front of a machine. So, my quilts are generally ultra simple patterns, often ones I adjust to suit my sewing style. As I read this post, it came to me that setting some sort of price per piece of fabric in a quilt might be a way to start estimating the cost. Of course, actual cost of the fabrics, batting, backing, thread and such would have to be part of the cost.
Since each seam in each joined piece of cloth takes time and effort, maybe that is way to start a cost estimate.