After searching online and at department stores for T-shirts to cut up and make fabric yarn, I finally found a shop on Arab Street (Bamadhaj Brothers) that sold a stretchy sort of jersey fabric. I don't think it's cotton, but that might be better at repelling dirt when I use it to make a floor cushion. I got 4 metres of about 1.6m wide for $35. I think that makes more yarn than 4 or 5 t-shirts.
Cutting it into a single strip was painful! I think it took about 6 hours, more or less. Couldn't do it in one go. Considering I bought it on the 2nd of July and it's now the 24th, I suppose I can say it takes me roughly 3 weeks to make a batch of fabric yarn, life included.
Wound as I went, to prevent a horrible mess of loose yarn accumulating, especially since I knew it couldn't be finished in one go. Grabbed the nearest handy thing to serve as a spindle, which happened to be a kids kaleidescope.
Took care to wind it as a centre pulling ball. It was tight around the spindle at first, but pulling out some of the middle yarn opened up more space in the centre so the kaleidescope could be pushed/pulled out.
SO glad it's done. Now I really hope it will crochet up well! More importantly, I hope there'll be enough for the entire project. Really don't relish the idea of buying more fabric to cut. Ugh. Next time I'll just go with the t-shirts, saw some at Giant Supermarket. T-shirts will cut up much more quickly as you can cut multiple layers at once. This fabric was rather thin and floppy. Maybe if I had folded and pinned it down properly it might have cut up faster. Oh well. That comes of barging ahead without really thinking it through first.