If I read correctly, this was initially intended as a gift to your daughter(?) then changed your mind because of the fabrics and this was hanging in the closet. Just based on that, it seems you weren't going to recoup any expense incurred from the start.
Given what's been established about your dear friend, it's not her place to establish the price in anyway.
Since she wants to give you some kind of monetary compensation, my thought is to let her have it and in return maybe the two of you could go to a LQS to pick out some new fabs that she could get for you, without burdening her wallet. She gets the satisfaction of contributing according to her limits toward your work, you get the happiness of giving the quilt that was to be a gift and now still is, you both get an afternoon of fun AND get to add to your stash.
Sounds good to me, IMHO.
What a kindness to respect her dignity when it comes to her financial circumstances, even more so because she appreciates and cares for your other works. To me, in this case, based on what you've said, that's priceless right there.