You could have an certified appraiser come and give you a written appraisal.
Insurance companies will accept that for loss/damage on a quilt (as opposed to replacement cost of a comforter from Kmart), they might do the same for the room.
And I don't think that's an unreasonable estimate.
I look around here and know it would also be a pretty high number.
That's just for the raw materials.
If you wanted your quilts covered for more than that, you'd have to get each one appraised.
But it might be worth it to you.
See what the adjuster has to say.
How does he value (hobby) woodworking studios, also with a lot of equipment and tools and inventory?