When other people might rather buy something, I try to build it myself and possibly also make the circuit for it, so I can call it completely my own. Only if it's worth the effort.
I would never try and build a DSO for example. It's simply too hard, and what I would achieve, wouldn't be worth the time spend. But I had build a scope with vacuum tubes once, which I took apart later because it wasn't build correctly.
The things I build will be used later continuously in some way. Otherwise I will take them apart and salvage some parts. Therefor I won't build HV stuff. It's useless from a daily use point of view.