You can self-host Marginalia [1] or Hister [2], for example. Takes up some space, but it's totally doable. Your biggest problem (assuming you have disk space) will be crawling.
At least if we're speaking a more generalist web search it requires dedicated hardware, that's pretty costly. Marginalia's production server cost about $20k back when RAM and SSDs were cheap. It used to run on $5k of PC hardware before, but that was very limiting.
So no data center, but at the same time, not everyone has that sort of cash to throw around.
Emphasis on "doable".
At least if we're speaking a more generalist web search it requires dedicated hardware, that's pretty costly. Marginalia's production server cost about $20k back when RAM and SSDs were cheap. It used to run on $5k of PC hardware before, but that was very limiting.
So no data center, but at the same time, not everyone has that sort of cash to throw around.