I got a used one on line from Ebay. Works just fine. It's not a difficult swap. You do have to remove the door card to do it. The nice thing is that the painted cover can be taken off the one you have on your X now and put it on the "new" mirror. That way it doesn't matter what color you buy as long as it is working.

I tried one of the repair kits on line and they don't work, so IMO getting a junk yard unit that works is the best way to go.