Coincidentally, I am going to HCM on Oct 23-25.
The Pentax lens assembled in HCM are perphaps meant for export. Can try to contact PENTAX VN Co., Ltd. / VIETNAM
Sai Dong B, Industrial Zone, Thach Ban Village, Gia Lam District, Hanoi, VIETNAM
tel: (84)-4-8750418 for local dealer.
The Pentax homepage does not register any dealer in Vietnam.
Can PM me if like to go Pentax hunting in HCM.