It sounds like what you want it some sort of HDMI over CAT6 cable with USB over the same cable as well.
I know you can push HDMI (or displayport) a very long way over CAT6 cable with the correct converters - I'm not sure if any of those solutions include remote USB as well - you'd think some do.
Any other solution means you need other computers at each endpoint.
China has lots of data centers that surplus out old equipment too - I'm sure they have their fair share of legit old pulls to sell off.
China also processes a lot of e-waste from around the world - I'm sure globally there were many millions of those cards sold. I'm sure they just pull and resell anything that's in demand.
That said, they also produce fake chips (or pulled / relabeled chips) and sell them for $5 in single quantities on ebay too - buying anything from China is a crapshoot. Even from the same seller/store but ordered placed at different times, one time you might get legit stuff, the next time you might get garbage.
The good thing about ebay is you can always get a refund if it's "not as described" - especially so if it's counterfeit.