I really believe that Tartan has the best idea. I believe that before you sell, you need to organize it. Just ruler folding will help so much in saving space. I have all my fabric ruler folder and in drawers, each drawer has a particular background color in it. But you can organize the way that works best for you. If you do clothes sewing, I would separate that fabric from the quilting fabric. If you have clothes sewing fabric that you don't or won't use anymore, then that would go in a separate area, to be either sold or donated. If you start in one room, don't leave it to work in another room until it's organized. I would read the criteria first, as far as selling on here is, one of the problems is that you can only list a few items at a time, which from what you've described would take years to sell here, I would list the fabrics on either Craig's List or e-bay to sell.