The Modern Citizen Kane? I hope you're fvcking kidding! Otherwise I woudn't be helping you 'cause that's just a downright retarded sentiment.
Well . . . anyway, first off ebay.com usually has tons of these, but they are also usually bootlegs as well.
You can also try Media Play if you have one in your area since it HAS been released already in the US. Next, if nothing prevails, go to dvdboxoffice.com or half.com, they should have some. It is distributed by Tai Seng (taiseng.com) as well.
Oh yeah, and that link is sorrect too. So try there, but last time I went there they never filled my order & its pretty hard to contact them.
You can import the officil Australian release(korean, Eng subs). It' s new. Region 4 though. You'll need an all regions player or a computer DVD player with out a region lock(though you can crack these with a simple download).