This thing does a much better job at cleaning their nano-texture displays compared to a regular, smooth microfiber lens cleaning cloth, so there is actually a reason for it to exist.
That being said, while I haven't tested this, you can get other "suede" style microfiber cloths that I suspect are functionally the same thing as the Apple Polishing Cloth.
I'd recommend flashing the cloth with open source firmware first. Otherwise it might check a signature in the glass, find that it's non-Apple, and become scratchy.
That being said, while I haven't tested this, you can get other "suede" style microfiber cloths that I suspect are functionally the same thing as the Apple Polishing Cloth.