I built one with a nice TUI to run on a VPS so I can try and find rare magazine torrents, but Hetzner were upset about it. I need to find it a new home. It was a very good citizen, but it still raised too many flags.
the seedbox is through https://www.feralhosting.com used them for over 10 years now and they've been great (shared hosting so I have linuxbrew setup there, but no docker sadly)
For cheap hosts look for ones that allow tor exit nodes if you're looking for ones that allow funny stuff. There are some that allow it for ideological reasons. Look through the hundreds on lowendtalk. On that forum you can even ask the providers directly if they allow it.
The other day it was trying to track down some older High Times issues that were torrented but the torrent is dead. Last night it was a mag titled Films & Filming which I know is scanned, but I can't find anywhere.
(no affiliation with them)
This year, I was giving it as an assignment to students. Does not take much time with LLMs.
Its algorithm is very elegant, using binary search on peers' and torrents' hashes, narrowing down to peers that are more likely to be seeders (or at least know some).