Check with a Bernina dealer. There was a wall hanging/quilt they did a couple of years ago that was made with silk. I think the kit was composed of fat quarters. My Bernina dealer still had a few of the kits a couple of months back. They were expensive though! You might also want to check with the Martha Pullen company. They have lots of silk dupioni, but I don't know their minimum cut size. They are very helpful though and might have another recommendation. If you want the name of my Bernina dealer, just message me and I'll give it to you.
Pam