Used appliances in Busan
Go to 좌천동, its 2 stops from Seomyeon. They have loads of places that sell used and new stuff. You can also go to Naver's 중고나라. It means 'Used Country'
I would have said Beomildong over Jwacheon Dong for used appliances. Jwacheondong is more famous for used furniture. Although I haven't been there for 5 years, so things could have changed.
Most of the places were located on the left hand side of the road and the streets behind if you were facing towards the Seomyeon direction.