I think a message thread like this is a good idea.

But maybe rename the headline of it to something else like "WARNING - THESE ARE NON LICENSED_ NON ORIGINAL_ NON SO CALLED FULL SIZED LAS VEGAS SLOT MACHINES_ BUT THEY ARE CUSTOMIZED JAPANESE PACHISLOS". (I know that is too long ....but you get the idea....)
Then whenever someone finds a custom pachislo being sold in auction = post it here. That way if a "newbie to the pachislo world" happens to pass by : the headline would catch their interest and just maybe we can save them the embarrassment of buying a custom machine. Especially customs that have Amercian/English themes with Japanese sounds and music coming from it.