Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Why would you assume that it is nickelplated, looks pretty much like a standard brass Mamod SP1 to me?

https://www.ebay.com/itm/384362057816

According to Mamod´s website, the SP1 appears to be discontinued (at least it isn´t seen in their shop anymore), and this appears to be a mint unfired example, which might be the reason for the $133 it brought the seller.