I got one from Amazon. It comes with 3m tape. If you can lick a stamp - you can install this spoiler yourself...
Edit* here is the link. It's an exact match to the OEM : Eppar New Carbon Fiber NT Rear Spoiler for Tesla Model S 2012-2016 (Matt Carbon Fiber) https://www.amazon.com/dp/B01MUJNTRD/ref=cm_sw_r_cp_apa_ONLnBbESBCE2J