Wandering around Jungang-dong, you may have seen Auck-Land (오클랜드). They always have lots of clothing outside for sale. It takes up two buildings and has a second floor, but the layout changes all the time, so its hard to say what exactly you will find. The have a large jean selection, but the sizes are still Korean. They also have shoes, dresses and sweatshirts.
The highlight of this store is the T-Shirt selection. It has the feel of a second hand store back in the US, with its eclectic selection of everything from your standard Coca Cola branded shirts, to artistically drawn birds, or robots, to the strange and unusual. Every few months the change their stock, so if you go and don’t find anything you like, wait a few weeks and the selection will change.
View Auckland (오클랜드) in a larger map