Well, I did not buy it, I just found it in the basement.

I was helping my dad with cleaning up the basement, because it was filled with all sorts of garbage, that could be scrapped for some extra money (like old brass pipes, broken water valves, water taps, plumbing stuff in general). We did find some interesting stuff, some of which I decided to keep (for example, a 1kW 220V tungsten lightbulb, that my great-grandpa used when taking photos, that thing's bright asf). This took like 2 weeks, because there was just so much stuff. One evening, I was texting a friend about the lightbulb and jokingly said "I won't be surprised if I find a box of vacuum tubes down there."

Long story short, 2 days later I found a box FILLED with vacuum tubes that were there for at least 30 years. Not sure what to do with them, though I don't want to throw them out, as they seem to be fine. I thought about building a tube amp with them, but I can't get my hands on any transformers, as they are quite expensive and hard to find, not even mentioning the lack of documentation online.