I know www.equilter.com has it.. and I have seen it in my Keepsake Quilting catalog, but it is definitely expensive. Have you considered using fleece like you can find at Hancocks, Joann's or Hobby Lobby? It is soft and would be less expensive.
Keep in mind that this type fabric makes the quilt much warmer than normal cotton and some climates don't get all that cold.
Barb C.