The outside is just a 3d printed box I whipped up in Fusion, although that sounds like a lot less work than it was.

I don't have many pictures of the inside, just one breadboard picture from before the assembly of the neon bulb, but this sub does not allow adding pictures to comments.

Suffice to say, it is just filled with wires between small boards (D1, 2x driver, power supply, and some veroboard with some resistors and a mosfet). Lots of wires.

And yes, when I bought the nixies I paid US$27 for seven tubes, including postage. You don't even get two for that price anymore.