I have been successful twice now getting Disney upholstery fabrics on e-bay, and I've seen others since then. I purchased a dark green/burgundy Pocahontas fabric that I did a seatee with and I also purchased a white/turquoise/red Little Mermaid heavy cotton duck fabric that I did a chair for my daughters room in. I have seen other fabrics listed on e-bay over the years that have been over-runs from the Disney cruise line. Perhaps if you just keep looking, something will come up.
I had spotted some denim with Mickey icons on it last spring at "Lens Mills" in Ontario. I was on the lookout for quilting fabric not upholstery fabric and so passed on it. Not sure if they have a website. Hope you find something.