Manitou Mattoc rebound knob

My 12-year old grandson has lost the rebound knob from the bottom of his Manitou fork. I have googled about and I can only find three places that have any. (all delivered prices)
Two are in Germany for £29 - £32 and one on eBay for £33.80 (also from Germany)

Does anyone know where I might get one cheaper or even a used one? Or maybe one of you good people has one sat in their tool box and it is looking for a home? :)

This is what it looks like; it's the blue one.
Click the picture top left to see the reverse side.

https://www.probikeshop.com/en/gb/manitou-mattoc-knob-kit-pro-rebound-and-air-cap-141-32155-k016/132533.html