Not disagreeing with the demand at all, but am thinking of the supply side.
He'll need to hold back the bulk of the spares for a reasonable time frame to cover warranty stuff. IRM did the same thing with A Class spares, and it's entirely logical.
Imagine Paddy ran out of spare wipers, for example, in the first few months, and it was common knowledge, then couldn't cover warranty stuff?
That'd be a nightmare for him and for his customers. Hopefully he considers them as standalone parts, agreed!
@WRENNEIRE had some spare handrails last year, so I guess they do appear from time to time.
And there are whitemetal spare buffers on eBay:
https://www.ebay.es/itm/155376010301