There are a lot of post all over the internet about the starter button. A post from Lee98 said that they are not available from BMW......
But they are out there....NEW!

I just received the buttons from Spain. Very nice quality. This gentleman is making new ones with the 3D printing method. I thought that I would receive 4 buttons as ordered but when it showed up there were 2 buttons and a new spring in each package. Very surprised and happy.. Cost was about 38euros for all + shipping.

http://www.hardtoptire.com/producto_...id_catalogo=19