You can go to Ben Thanh market, they have many knid of Vietnam fabrics but so expensive. More cheaper than have many place. That mean Tan Binh Market ( Ly Thuong Kiet Str, Tan Binh Dictrict ) or Cho Lon Market (Thap Muoi str, D6 ), Soai Kinh Lam Market ( Tran Hung Dao str, D5 ) . You can refer by internet, and you can take taxi go there. i think you must have a vietnamese friends go together.