"I have contacted a couple of the members who left this member negative feedback and they have said the same thing, that the buyer asks for the item to be sent first and will only pay once they receive the item"

With the type of items you're selling, it either sounds like a new member who has just joined and bid on things for fun with no intention of paying at all ....... happens all the time

Or

It could be a Scammer .

As advised already, put all your buyer blocks in place.

Always beware of spoof/phishing emails you may receive and run all your spyware, keylogging and virus protection and change all your passwords regularly.

As far as the suggestion above to report the Sellers who have left a brand new ID positive feedback with a negative comment under these circumstances , that's utterly ridiculous IMO