They probably don't if they don't have an English option :(
http://shop.broccoli.co.jp/maker/arcsystemworks_shop/
There's some cool stuff there. You know Ben wants that coffee mug of Jubei! The "hope" shirt is pretty nifty, especially since the proceeds are going to the relief to help Japan.
Some game companies in Japan ship internationally (Grasshopper, Cave, etc.) but most don't so your only (and costly) hope is using a deputy service.
You're not without hope in other areas! The European publisher, Zen United, opened their own shop with a handful of BB merch
http://www.store.blazbluegame.com/index.asp
Seems like they're planning for more when they release Arcana Heart (and Guilty Gear?). Since they have a currency conversion for the U.S. and Canada it seems they can sell intentionally, so look it up!