Looking for this trunk with the little lip for a 2012 G37x cannot find anywhere looking to be pointed in the right direction

 

That's the OEM sedan spoiler. These are becoming about as rare as original copies of the Beatles White Album.

I checked Amayama and they don't even carry it anymore: https://www.amayama.com/en/part/nissan/k60301nf5a

Two options:
1.
Find a salvage yard with a crashed sport model and buy the trunk (they may break the spoiler trying to get it off)
2.
Find one on eBay aftermarket that is close (still amazed that nobody makes an aftermarket copy). A member here has one that is very close, but I cannot recall which member. Maybe they will see this post and respond.
2b.
Buy this one and have it repaired and paint matched (make sure it has the cutout for the camera if you have one): https://www.ebay.com/itm/167976624172