That looks like a developer's machine to me! When they were working on Brilliance, Digital Creations had a couple of these black A4000 prototypes. They had Brilliance well on its way before the A4000 was actually released.
Didn't see the inside, heck...I was under non-disclosure and wasn't allowed to talk about even having seen one at the time.
I've seen one other A4000 prototype since, in the pile of machines at 4 Jays store in Antioch.
Your machine is truly a rare bird! Good luck on the auction.