Nice tool, especially when looking at refurbished disks.
But for new disks, in Germany you can use geizhals [0] to cover many more shops than just Amazon:
Cheapest new disk on Amazon.de is 18.43€/TB (the 15€ unit is refurbished) while geizhals lists 16.24€/TB shipped.
Also available in AT, PL and UK, though I don't know how well these are covered.
Also available in AT, PL and UK, though I don't know how well these are covered.
[0] https://geizhals.de/?cat=hde7s&sort=r&hloc=at&hloc=de&v=e&t=...