Oh, you are in for a treat. You will love these places. I visited there few times, but I was not into quilting then, so don't know about specifics for that. I am sure hotel staff and locals can guide you to fabric stores there. You'd probably find many in open-air markets, and you'd be surprised at the high quality of materials you can get at a very reasonable prices. At least that was my experience with clothing and such. If I were you, I wouldn't take many fabrics for trade (I don't know how much trading you'd be able to do) to leave space in my suitcase for goodies I'd be buying, remember weight is limited.
Have a safe and wonderful trip, you'll love it!