Three weeks ago my brother flew from San Francisco to Seoul. As usual, he asked my mother in advance what she and my father wanted him to bring as presents.
Answering him in our family chatroom on KakaoTalk, she wrote, "What could I possibly ask for? Multivitamins, coenzyme Q10 and omega-3 oil. I'm sorry for the requests."
She is genuinely contrite about asking, but it makes sense to do so: such health products are certainly available in a metropolis that is Seoul, but they are rather overpriced (60 capsules of omega-3 oil can be had for less than 6 dollars in the US but sell for far more in South Korea).