Replacing the assembly is the only way to get a new one. The dealer I use has them listed for $146 each.
For used ones try
http://car-part.com" onclick="window.open(this.href);return false; or ebay.
After toolguy disappeared, and one of my fog light covers went missing, I installed a set of Yellow Lamin-X covers to keep the glass safe. I've been completely happy with the Lamin-X product.