You know, Boedhi Adhitya has a good point. The same is true of Japanese nihonto sword collecting. Getting together with those who collect, ie. forums (like this one), associations, etc, will help us all on not getting taken. I had a Japanese piece that I discovered was a Paul Chen and was able to get my money back (due to the honest dealer and the feedback of the nihonto guys on the swordforum.com).
