Well they are not really "shinza bags" as shinza is just exporting the bags from Japan. Elecom(a japanese company) is the maker of the Zeroshock bags.
elecom zeroshock website
Not sure if it's worth it yet, though since I barely ordered one for my 600m(black 15" medium zeroshock). I ordered mine through a different company and they didn't have it in stock(they have to get it from Japan), so it will take about 3 weeks or so to get mine. But it's only costing me $21, so I'm not complaining. :-D