I'm not sure if this's the same underground shopping that I went or not. I went to one at Gangnam area and it's named Express Bus Terminal underground shopping. If you're looking for bargain clothes, this is the place for you! Prices ranged from 5000w and above but normally from 5000w to 20000w. Crazily cheap! The underground shoppping is really long. Prepare about 2-3 hours to shop if you are really into buying clothes. I spent more than 4 hours there while my friend even went back again the next day. So much cheaper than Dongdaemun. While Shinsegae Department store is just next door. Hmmm not next door, they're both connected. Go to Shinsegae food court---it's another HEAVEN! If you're more into branded goods, then you should go to Shinsegae Dept store. If you're after both branded & cheap goods, spare a whole day here. Trust me, it takes a whole day to shop here.