I do buy ancient and medieval Chinese cash coins on
ebay. About my 10th year of doing so. You do have to know the integrity and knowledge of your dealers. And you have to spend time learning about the coins that you're going to collect. So that you can spot suspect coins yourself.
If you do the above you will find authentic Chinese cash coins to buy on
ebay. But if you go in blind and uninformed that is VERY risky. You will get taken at some point.
I just wanted to say that the answer isn't to avoid all Chinese sellers. I know from experience there are some very honest and trustworthy Chinese
ebay sellers. And nice people too. Not every Chinese seller is a crook. (Granted and unfortunately, a lot are though.)
The answer is to be educated. But that does take some time and work.
Note: Regarding the second seller listed in the first post, best66666. Some of his coins are obvious fakes, but some are really good fakes. Stay away from that seller. He and his many "coins" are dangerous.
The first seller listed, threekatsforyou3, seems to just be selling miscellaneous junk. He doesn't appear to be a career fake seller like best66666.
On a lighter note. If more and more people stay away from buying Chinese cash coins on
ebay, that's OK. More coins and less competition for me!