The first thing is that the directions here need an update. When you exit the subway station the bank is to the right. As the description states everything is in Korean including the sign with the name of the buffet. This is what the sign looks like in Hangul 남새뷔페. The restaurant will be on your left hallway down the second block directly across the street from the CS store.
Now, on to the food. Being a vegetarian in Korea is very challenging so I expect that it's hard to keep the doors open at a vegan restaurant. My guess is that's why the prices are a little steep. However, the food is stellar and completely worth the price. There are plenty of choices and everything is excellent. If you're in Busan, hit this place up!