Around the turn of the century I used to specialise in Solaris contracting, so my homelab back then was mostly old Sun Enterprise gear from Ebay.

* https://en.wikipedia.org/wiki/Sun_Enterprise#Entry-level_ser...

Used to have an E450 (like the one here: https://en.wikipedia.org/wiki/File:SUN_Ultra_Enterprise_450....), and a bunch of other, smaller stuff (workstations). Also an E220R at some point from rough memory. No idea what happened to all that old stuff.

Anyway, it was extremely useful for interview prep (aka brush up on specific skills) prior to meeting potential new clients, and also for doing general dev / packaging stuff on.