I know when I made my son's quilt (my avatar), I kept track of just the materials used and that was almost $400. That didn't include the tutoring I needed to make the flying geese circles and learning paper-piecing, etc. etc. etc.
Since this IS a "one-of-a-kind", I've seriously considered having it appraised and getting it insured. My quilt instructor said it's probably worth around $2500.
When my son comes home for a visit, he brings it with him so he knows where it is....makes me feel so good to know how much he loves his quilt.