Received my Korean-made magnetic goban
from Yutopian. With this model, each stone's magnet is sandwiched between two identical plastic halves so you have a whole
stone. This means that you don't have to flip the stone to have its magnet-side down on the board (unlike other models I have seen sold on eBay).
The price is about the same as the smaller Japanese-made version sold at Kinokuniya Bookstore in San Francisco.
The stones rattled in the plastic case so I bought some black felt, with adhesive backing, from Michael's and lined the insides of the drawers. It quieted the stones considerably and gave the goban a classier look and feel.