[icebraining]

It probably depends on what you're using, but my experience (self-hosting email with exim + dovecot, RSS with TTRSS and now calendar/contacts with Radicale) is that I barely have to touch them after setting them up. I use unattended-upgrades to keep the box updated with security fixes, and every few years there's some new email anti-spam thing you need to setup, but other than that, I don't touch it.

As for cost, I run everything on a $5/month DO box, and it's only using half the ram and barely any CPU. You could run it on an even cheaper VM or even a tiny physical box like a Raspberry. Backups are just a matter of using a tool that encrypts and syncs to some offsite.