This is the polishing cloth used in the Apple stores to clean off/polish the demo units in between try-ons. It's a real Apple product, though only intended for internal use.
I looked up the listing you're talking about and it's way overpriced. Chargerstore, a very reputable China based seller who has done lots of business with countless members of the thread members here, myself included, sells these in packs of 2 for $12. You can contact him directly if you want a whole box of them, though. Not sure how much he charges for that.
For 2pieces Apple Polishing Cloth(Midnight blue color). 100% Original Apple Polishing Cloth. Apple polishing cloth 2(No box included). Photo#9~#12 are for a box of cloth comparison purpose only.
www.ebay.com
Didn‘t the original series 0 gold edition is come with a blue cleaning cloth?
Correct. Original 18kt gold Edition models came with pretty much the same exact cloth, only instead of saying "Watch" on it like the ones given to stores, it says "Watch Edition." Still, under that, it's the same cloth. (the text on these fades so quickly anyway, after a week of using it you wouldn't be able to tell.)