I would check on barn light electric to see if they have them or something similar.

FYI I liked a light fixture in the Pottery Barn catalog a couple years ago that wasn't for sale. I called them to inquire and was told to be patient and it just might show up in the future. That was right it was a year later and there it was in their mag for sale. I hadn't waited so didn't end up with it but I think they do that to see if there is an interest.

Check restoration hardware, looks like something they would carry !

You also might try a company by the name of Rejuvination Light Fixtures. Ebay also has some great finds.