Get the amazon one. I had an OEM and Amazon and frankly couldn't tell the difference. Don't waste your money on OEM.
I got one for my 2017 Tesla model S from Topfit on Amazon,If you would like to see the picture I can send to you.Please suggest a CF spoiler for 2018 MS. My budget is $200. Looked in amazon and ebay but could not sure which will be reasonably good.
Thanks for your help