I agree with Parrothead.
The only term that I can see using the word "value" of a quilt is a really historic piece, such as from the Civil War, etc but even then I can't equate that kind of value with money.
And also justflyinin's post- again I agree. Cotton deteriorates, sadly. I've seen museum quilts that are climate-controlled but of course, not for sale. I wonder how long they will hold up.
I saw President and Mrs. Lincoln's Inaugural clothes recently at a DC museum. It was awesome!!