Mods, I know this thread doesn't follow the specified form, but I wasn't sure of where else to put it (I searched but couldn't find anything similar). Please move it if you feel it's better placed elsewhere, thanks. 
So it seems, like I've screwed up and been had by a scammer, or at least just a dodgy bastard, on gumtree. Pretty pissed at myself for it really, I got impatient and carried away, and did some things I normally wouldn't.
Anyway, I figure the least I can do is put out a warning in case anybody else stumbles across the same guy trying to pull something similar again.
What I know:
Name: John De Jong
Gumtree ID: jdejong
Location: Cundletown NSW (near Taree)
Item: Marantz 6008
Guy new enough about gear to make it believeable, said he had recently picked up a Yammy 3050 cheap (which seems about right from what I've seen) and was selling the old AVR off.
Photos weren't reused ones (Google image search can't find them anywhere else) and we were going to meet up on the central coast, but I got impatient and decided courier would be ok; it wasn't.
So keep your eyes open, hate to think anyone else falls for this as well.
On another note, if anyone happens to be getting rid of a similar receiver (particularly a Marantz), let me know. I need to save a bit longer now but I am still interested in moving up from my cheapy Yamaha.