Hey GregZo,
of course you find no-name chinese counterfeits for a fraction of the price in the www. What is important is to be sure that when you buy one, it is really for the specific Molex / Amphenol contact used on the Onefinity. The crimp connection is only safe if it matches.
I own a crimping pliers with interchangeable dies, so if I wanted to make some custom length cables for the Onefinity, I would buy the Die for connectors in the Mini-Fit™ series from Molex LLC, but I saw it is much more expensive than any other dies that I own, it’s about 200 €, while usually the dies are at 50 €. So maybe the pliers and the dies are so expensive because of licensing fees. I don’t know.