Well, Libby Leman told us she charges $400 a square foot for her quilts, and has no problem receiving that much. Of course she is an award-winning quilt artist, having a quilt chosen as one of the Best 100 American Quilts of the 20th Century.
I would not make a quilt for minimum wages. On the other hand we don't have the resume Libby does, at least I sure don't! :D But, it does give you an idea of what "art" can be worth. So, your quilt (art) is worth whatever you think it is, don't undersell yourself.
Have you considered having other one (the one they watched you make) appraised?