Scott, the owner, is super helpful and friendly. Feel free to ask him anything and he will do what he can to help you. The guesthouse has shared rooms as well as single private rooms at very reasonable prices. For example, my private room with private bathroom/shower was only $30 a night. Every room is equipped with a TV and, of course, the entire place has wireless internet for its guests.
As you walk out of exit 1, turn at the first right and go up a steep little hill, then make a left into the very first left (small alley). Kimchee Guesthouse will be on your right before the end. Link is on the bottom.
https://kimcheeguesthouse.com/seoulstation/