I'm in the U.S. and ordered most of mine from HMV in Japan. link
Most pages are available in English if you select it in the upper left corner.
There is also CD Japan: link
I find that they usually don't have what I'm looking for in stock though. But they have more choices for shipping so you can save a little there.
But even with the shipping at HMV, you end up getting stuff way cheaper than if it's already imported at Amazon or CD Universe type of places.. much cheaper to import it yourself. I recommend HMV Japan for reliability and having stuff in stock that ships fast. The 2004 versions are listed there as 'paper jacket'. There should be all 15 studio albums, and 3 live albums available that way (I wish they'd do the hits albums too, to complete the set!)
Or, you can find them on Ebay. If you have trouble locating these editions, try different search terms like paper jacket, mini vinyl, card sleeve.
They were sold in the UK in stores, but in other parts of the world I'm afraid we're not so lucky. What you might be able to do is find a local store that will special order imports for you.. you could call around and ask about that.
But then you're probably gonna pay extra of course.
I start using Amazon.com right now. Ordered 4 CD today, but I'm very scary - they can send me 2001 instead 2004. Average price ~ $30. Better than nothing. :(