The 2 spare tips (1 white & 1 light grey) can be found in the packaging with the pen (in a small plastic bag BEHIND the box where the pen is inside).

Attention!
Only later did I discover that 2 replacement tips were already included with the S3 as well as the S6 tablet(s) (check the original packaging!). They can be found in the small bag with the metal clip). There is a video on YouTube on how to replace the tips (it's very easy).

I hope this information helps.

Type in "replacement tips for Samsung Pen" in Google and you will find them at the dealer with 4 letters, starting with W.

Hello on the spare parts page from Samsung (samsung.sparepartservice.shop) you can order these tips.

It's a scandal, I called Samsung yesterday morning, they send me here and there, no one has the replacement tips. They finally admitted they don't have the spares!!!? The impression is that I want to sell a new pen.
So I ordered them on A..zon in Italy (5 pieces 10 euros with shipping) and already received them today (delivered in Italy, I live on the border).
Bad service from Samsung