Yes it is down. The materials cost (by unit) 20.25 per meter of cuben, 5 dollars thread, 5 dollars needles, and 150 USD thru-hiker quilt kit (5 yds momentum, 2 mesh, 12 down). Total cost: Approx. 261.25 USD however this is with tons of momentum, mesh, and some cuben left over. Also, this is the price of CT1K.08 weight cuben from Cubic Tech and does not include shipping and handling for any materials, but the lighter weight .33oz would be cheaper. Buying cuben from quest or zpacks will cost more, so I would suggest trying to find someone to split the minimum order of 9yds with you from cubic tech like I did. If I didnt get the cubic tech order, I would probably have gone with the zpacks CT1K.08, their price is very good and Joe is great. But going with cubic tech will bring the cost down considerably.
Its pretty economical. I was able to get the quilt and vest materials for 260 USD, and I still have approx. 30-40 dollars worth of materials I could sell back. I was planning on spending much more for a sleeping bag, and am already on a super tight budget, so it worked out well.
If you do end up making one feel free to shoot any questions my way and I will try to help, assuming I am on the computer (probably not the next few months!) Tim and everyone on the site were really great in helping me out with making it as well.