I just placed an ad on the national PCA website:
https://mart.pca.org/ads/48125
I have a left rear (drivers side) tail light for sale $150 for a 2013 Boxster S. I also have the right rear tail light for free (has a crack).
Here is a link to some photos: https://photos.app.goo.gl/83D3bVztURToyQMz9