I think the plain and simply solution to this is and has been said many many times over is to deal with members from both forums. If the seller does not identify his or her self as a forum member then the buyer is on his/her own.
Yes, we are here to help. But we can't help everyone, and that goes with eBay buyers.
On the other hand, granted there is one product by different sellers/names. He or they are selling one item only. Who is to say they aren't legit?
I'm not defending this person/s. By all means no. But like everything in life, be cautious..
Complaining to ebay isn't going to get nothing but heartache or a headache. Ebay is making money out of these sellers, so unless you can prove the seller is doing wrong ebay is justing going to brush you aside.