Buy from authorized dealers. If in doubt, contact the maker(s) to find out who they may be. Too many folks don't care about the legitimacy, and would rather get something that looks like the real thing at a cheap price. Like fake Rolexes and Luis Vuitton luggage.
I agree that it is sad to see people taken by hucksters. And they will always be around as long as there is a profit motive.
You can discuss what to look for in determining a legit knife from a clone, what you can't do is point out where to get them.
If someone asks if their widget is real or one they are thinking of buying is legit, they can share an image and the "experts' can point out the salient features.