Polomon.com is offering Windows 10 Home + MS Office 2016 Pro package for $29.99 USD. There is a $3.59 USD off for this pack: Windows 10 is $9.59 USD & Office 2016 is $23.99 USD selling separately.
This is a new site, but as PayPal is the only payment method, it should be pretty safe to purchase for consumers.
These sites often deal in keys purchased with stolen credit cards. No way this is near Microsoft retail in any market. I would avoid it.
or academic keys being resold
They have phased (or are in process of phasing) those out. Academics now get Office 365 licenses while enrolled/working
Should block these sites
As I've said previously, I don't trust polomon.com at all. The site is only 3 weeks old.
Their contact email is at gmail rather than their own domain.
The prices are too low to be genuine. Your keys could be disabled by Microsoft at a later date.