Tips that have helped me find out-of-print fabrics in the past:
Go to the original manufacturer's website. A lot of them will show past lines complete with SKUs, and I have found the exact print using the SKU number to search with. When you have the SKU, you don't have to depend on whether the picture matches or not.
If you can't find the fabric that way, contact the designer. Most designers get a full set of the fabric line they design. I've been able to purchase fabric directly from the designer's personal collection on 2 different occasions (2 different designers).