a recent article said to figure the quilt size in square feet
55x75=4125/144= 28.6 sq ft.
then multiply by either $15 for sq ft or $20 for sq ft
$15x28.6= $429.68
$20x28.6= $572.90
As a guide this works fairly well. Just remember to get at least 50% down before starting. If special fabric then add the extra cost also. one baby quilt cost me over $50 just for the theme fabric, be wise .