Eurpoean suggestion for cheaper windows 8.1 key

Good morning my fellow Teknicians.
I'm at the closing stages of collecting the parts for my PC build and I've finally come to the O.S.

As I am not yet confident enough to try out Linux I'll be sticking with Windows, (Windows 8.1 to be precise).

Anywhoo, the Keys I've seen on the irish estores are in the €120-€140 area, and I was wondering if anyone knew of a way to get a legit key for a bit less?

Thank you.

Any US retailer should be fine. There was @digitaljuice selling keys on the forum a few months back but those started to have issues.

Windows keys shouldn't be region locked afaik.