Do you have any idea of when the photo was taken? The older the fabric, the less likely yardage of it can be found.
eBay tends to be a good place to look for older fabrics. I just went there and searched on "princess fabric". It came back with 35 pages of items. I looked through the first 2 pages (thumbnail pictures) and didn't see this fabric. Maybe you will have the patience to go through all 35 pages. You can also put in a "saved search" so that each time new listings come through with the words "princess" and "fabric" in the title, you will get an email notification.