I have a couple of Moroccan Djellabiyah's from some travels of mine.
But, for the full Fremen look - I've a "Silhem" cloak. Spelt سلحام (I think).
I certainly did not pay that much down some back streets in Morocco as I have seen on a few on-line market-places though! Was great, and saved me when I was out camping in the desert and it was very cold. Not been terribly useful in the more damp Welsh climate, but great around the house and in the kids' dressing-up box.