How can I purchase non-industrial amounts of raw cotton?

Question

I am making old-fashioned futons (heavy Japanese quilts). My great grandmother always layered raw cotton between cotton batting.

Answer 1

When I did upholstery for my car, I purchased raw cotton from an upholstery supply shop to go on top of the foam padding. It was sold in a roll (but it was just raw cotton) and was inexpensive. I imagine it would do perfectly for a futon as you described.