I still got several nixie tubes somewhere in my home. I bought it from Ukraine on eBay before I go to college. I was hoping I can learn something about designing high voltage PCB during college, but then I forgot it and learned computer science.
I saw someone build his own collection of nixie tube clocks, which I think is here:
Super recommend, such a beautiful thing.
Sadly, no one makes Nixie tubes anymore.
https://www.daliborfarny.com
They have some hand maded tubes, but seems like they don't sell the tubes anymore.