How long did it take to baste, quilt, and bind. Add up all these numbers and divide by the number of square feet in your quilt. That's how long it takes to make one square foot of quilt in that style. Now you need to decide how much your time is worth. This is the rate of pay for unskilled, entry level jobs.
Skilled labor is worth more.
Once you have decided on a number for your hourly rate of pay, you need to multiply that number of hours it will take to make your quilt. Suppose that you are really speedy and you can actually design, piece, quilt, and bind a square foot of quilt in 2 hours. So your quilt will take 33.32 hours to finish. That's just the starting figure. They are probably going to want a commission.