The prices are taken from a ExplainingComputers Video at 3:35

For the Pi it includes the Active Cooler, M.2 HatDrive and PSU.

For the N100, besides the board also RAM and PSU.

Should have been clarified in the article.

There is the Nibelungen saga, a Germanic folk tale. It is too complex to give a short summary. Part of it is the heroic story of Siegfried, the dragon slayer.

It is western and well known in Germany, but judging by the lack of English sources, not very well known elsewhere. For more, I recommend reading the German Wikipedia entry (with translation)