I've just recieved an e-mail which seemed to originate from the winning bidder on a recently sold item which says (exact quote)

:x
"Hello
i want to close this deal.What is the final cost including shipping?
waiting for your quick reply.thank's".
It seems to be a legitimate message from an e-bay member, but when you click respond, it takes to you a sign in screen which looks very much like e-bay's sign in screen.
The member that it pretends to be from is "pc_made2510". I've checked with e-bay and that member does not exist, so if you get a message originating from any name like that (it may be a random name though), report it to e-bay.