From a April 1st 2001 game magazine. Now that Virtual Hamster and Xmen has been released maybe a Neptune is right around the corner. A brotha can dream.
April fools joke...in case you didn't know. I think a single Neptune mock-up does exist, forgot who owns it though.
There are only 2 units out there AFAIK, one is just the shell and the other has internals but it wont boot.