I just wanted to update this thread in case anyone else is looking for a set. There is a seller on eBay selling aftermarket BMW style Performance Side Skirts.
https://www.ebay.com/itm/114305865740
Made off a thick molded ABS plastic, w/ mounting holes just like ORM. Good quality and look exactly like the BMW style. $300 with shipping from EU. I pain $325 to have them painted and mounted locally.