Daiso in Myeongdong: the Main Store (43 Myeongdong-gil) and Myeongdong Station Store (134-1 Toegye-ro), both 10:00-22:00. Daiso prices are round numbers like ₩3,000 or ₩5,000, so checkout is easy. LG H&H's Innerview Lutein Zeaxanthin (30 capsules) is ₩5,000 with 5,822 orders. Capsules aren't liquids, so they're fine in carry-on, even if the box gets squashed.
Daiso Mall
Daiso MallDaiso Mall