The NeXTBus dev board was nothing special at all. It was just a breadboard PCB with grounds and power traces added. The holes at the back for ports were for the end user since you can't buy connectors that plug into the grid conventional pattern. It looks a lot like someone started work on something but then gave up. Components are missing but the board shows no signs that they were desoldered.
I have NeXT's description of the board alongside a photo in their 1990 Products catalog. They were trying extremely hard to get vendors to build NeXTBus peripherals but even at $350 for the NBIC, full documentation and the board they didn't sell a lot of them (which sucks because they were literally telling people to go wild with the hardware).
What IS however special is the NBIC chip that linked your prototyping to the NeXTBus. It's missing from this board. Again, doesn't look like it was ever installed.
Without it, that was just one VERY expensive square circuit board with a NeXT logo. I hope the buyer knows that the board is neither all that valueable or useable.
Edited: It seems the catalog photo shows a board with a different layout where all the rear connectors are just what you would of expected on the older 030 cube boards (DSP, Serial, SCSI, Printer, Ethernet, Monitor).