Looking for an apartment

So the school I'm starting in March is in Gangnam so I'm trying to find housing outside of gangnam. I used to live and work in Gangseo-gu and I enjoyed being on the express line so I'm leaning towards that area, but morning commute is the thing that's stopping me.

Does anyone have any areas they recommend that have affordable housing?

Edit: school is giving me 700000 a month for rent