This is a beautiful quilt. The lady has purchased from you before and so knows the quality of work you produce.Besides cost of fabric etc. and time, I think you should add in most of all your creativity. This is not a bedspread and it is not anything you would ever find in a store.
A lot of people could not afford this quilt, but I will tell you there a many, many that could-it is not right to deny people with money the right to buy lovely quilts!
I think the members of this very knowledgeable board are steering you in the right direction--$1200-$1500.
quilts!