This is not a shop. But if you are visiting the Kirklar Kilesesi Syrian Orthodox Church in Mardin, the young wife of one of the church officials there may offer you some homemade wine. They sell it there, and it is well worth the price. This bottle of Syrian Orthodox wine was one of the best souveniers I brought home from Turkey. Alas, it didn't last long!
Many shops in Mardin and Southeastern Anatolia.
What to buy: Mardin, especially Midyat area is famous for their silver jewelry art. Jewelry making is the ancient art of the Syrian people.
What to pay: Depends on the weight and detail of the piece.