In Myeongdong, go to Daiso Myeongdong Main (43 Myeongdong-gil) or Myeongdong

Station (134-1 Toegye-ro), 10am–10pm. The 150ml toner is ₩5,000 (6,700 orders) but over 100ml, so check it in. The 15ml spot essence is ₩3,000 and fine in your carry-on. Both together cost under ₩10,000.