I would guess that the real issue is that there are a fair number of "gray market" sellers on Ebay, and other places. An online seller called "Comet Supply" used to sell Denon cartridges, and I'm certain they were gray marketers, though I never had an issue with them; they've since ceased distributing phono carts. I have also bought from innovee-tech on Ebay, and haven't had any difficulty with them. A genuine Denon does come with a spec sheet showing what the factory tested each channel's output at, and that is included with the information packet in the box, along with a small white brush for cleaning the stylus.

Speaking of Ebay, there was a seller who was blowing out his stock of aluminum bodies, and I bought a couple. I've since put 2 of the 103s I bought from innovee-tech into them, and potted them with non-magnetic electronics epoxy. Anyway, I see he's changed his design and the current iteration looks more like the body version Zu sells now.