Lost the link now but I found a decent one on ebay for about £55. It came from Taiwan in about a week with perfect fit and colour match. Not risky at all buying Taiwanese, I was very impressed by service and quality.
Hi
I've just removed my Obsidian Black C63 spoiler if anyone is interested. It's an OEM spoiler supplied/fitted by my local Mercedes dealer. Cost around £400 including fitting.
Personally I would always buy genuine parts. I know a lot of people have had bad experiences with the Chinese/Taiwan/imported c63 carbon fibre rear diffusers but can't speak for the spoilers.
As for fitting it's very simple and easy to align. Purely sticky back 3M tape. Could have saved myself £70 :/