There seems to be some natural law of Internet shopping that ensures that every "Specialized marketplace for X," will, once it becomes popular, inevitably devolve into a flood of thousands of sellers all reselling identical cheap junk from AliExpress for $0.99 + free shipping--to the point where it's impossible to find anything genuine or non-counterfeit.
A magic number analysis of the images used in accounts would handle pretty much every duplicate found (which would highly hint at mass-reselling) unless the people got smart enough to figure it out and start jacking with the color palette.