Daiso in Oasis have plain red ones - fabric - 8 dhs or Marks and Spencers have more expensive ones!
I got the M&S one. It's lovely, big and soft with a picture of Santa on it. I do always walk out of there with my wallet feeling much lighter though!
It doesn't have to be anything special - just a plastic sack with Christmas pictures on etc? I looked all over Dubai Mall but couldn't find one. Has anyone seen one recently?