I found some Japanese fabric at Purl Soho and thought you might want to check it out. You go to "Japanese" under the "Style" heading. I didn't see any silk, but I didn't look at every fabric. Mostly they have cotton and linen. Some of the prints are quite crazy, but others are unmistakably Japanese. Here is my favorite. I want to buy some so badly, but what in the world would I make?
Here's some that I thought looks very Japanese-ish. It's $16.50 a yard and says that it is Home Dec weight. You can find it under Kokka Fabrics - Mameyakko.