Many people have created their own 3.9 ROM images using a 3.1 ROM as a base and then adding in the additional 3.9 modules that normally get loaded by SetPatch. These images are typically softkicked using Flash memory, like the Algor or Deneb USB card, thus providing a de facto Kickstart 3.9.
A few users have burned these images to actual physical EPROMs. Each set is probably different, since each user will have assembled the images using different modules.
Someone might sell you one of these custom sets in a hush-hush private transaction. Amiga shops can't sell them because it exposes them to legal liability.
