Best place to get windows 10 keys?

Where is the best place I can purchase a cheap windows 10 key. UK/England links please Home edition would be enough for me.

I bought windows 8 pro license earlier this year on G2A, then upgraded it to win 10.

Total cost: $25

G2a / kinguin
Just be sure to pay the 60p protection thing and arguably use PayPal alyhoght I've never had a problem and I get all my steam keys and windows once too