I had a friend that stumbled upon about 20 1-yard cuts of vintage (authentic) 30s prints. Pristine condition, all colors of the rainbow. It was bringing about $50-$75 a yard, when she put it on ebay, and people were emailing her begging her to sell smaller pieces so they could afford to get in the action. So..she started selling 1/4 cuts. They still went for $25-$30 for a quarter yard. I think she made a couple of thousand on that lot - and she is not even a quilter. It was gorgeous, and I was drooling, but certainly not willing to pay those prices.
And yes.. the Japanese buyers were going crazy over juvenile prints for awhile. And later (not sure if they still are) over the 60s pop fabrics, especially anything with stylized daises on it.
And I did quite well myself selling vintage scraps - mostly from the 40s. One lady bought quite a few of them, and since they were such small pieces I asked her if she was making doll clothes. She wrote me the nicest email telling me that no, not doll clothes. Turns out, she is a children's book illustrator and uses the fabrics as inspiration for her illustrations. Very interesting.
I am sometimes surprised at how much something will sell for, especially when you get one or more buyers with lots of moola and they start a bidding war.