seeing as the OEM is a simple flat mirror, any Goodwill, or similar used stuff place would net you an adequately sized glass mirror for $2, easy peazy to cut with a glass cutter $8 at Lowes, and smooth the edges with some emery sand paper on a flat countertop... add some 3M double stick Trim attachement tape from AutoZone, and viola... done for less than $15...
lots of youtube videos to show how to safely cut glass and mirrors, it's easy once you do it once or twice...
the secret to cutting curved shapes is learning to do the Tap tap, tap on the rear surface to make the glass shape break free..cleanly...
I learned this as a kid, when I had a kit for cutting bottles for making vases and such...
https://www.youtube.com/watch?v=RQSFnk28yFYthe tap thing works better than trying to pry the boarders or edges with pliers...
https://youtu.be/RQSFnk28yFYI've done a bunch using simple mirror tile 12x12 from Home Depot, or Lowes.
Just make sure the stuff is clean, dry, and warm before trying to stick it on...