Why is basically the same room 200k more in Gangnam?

Almost entirely location, with a small amount of building quality mixed in. The room really is close to the same room.

Rough Seoul bands in 2026 for a comparable room with a window and private bathroom:

- Gangnam, Seocho, Jamsil: 600,000 to 750,000
- Hongdae, Sinchon, Itaewon: 500,000 to 650,000
- Anam, Hoegi, Konkuk area: 450,000 to 580,000
- Noryangjin, Sillim: 400,000 to 550,000
- Outer districts on a subway line: 380,000 to 500,000

What you are paying for in the expensive districts is proximity to offices and nightlife, not a better room. For a language student whose campus is not in Gangnam, that premium buys you nothing.

The sweet spot for a student, in practice: a neighbourhood one or two stops from your campus rather than adjacent to it. The price drop from "walking distance" to "one stop away" is often 80,000 to 120,000 won for six extra minutes.

Where I would actually look, depending on school: Yeonnam and Yeonhui for Yonsei and Sogang; Jegi-dong and Hoegi for Korea University and Kyung Hee; Sillim for Seoul National. All are meaningfully cheaper than the adjacent student strip and no harder to live in.

One caution on the very cheap outer options: check the commute at 08:15 on a weekday, not the map distance. A 500,000 won room that costs you 50 minutes each way is not a saving; that is 8 hours a week for 100,000 won.

And Noryangjin deserves a specific mention — it is the exam-cram district, so it has the densest goshiwon supply in the country and prices to match. Good value, slightly odd atmosphere, and worth seeing before deciding.