@EclecticEclipse I used to run a Zimbra server at home. It worked well, but was a lot of work.
If you’re just looking to cut costs, I’d recommend Zoho as a host. They have a simple privacy policy and features comparable to Gsuite.
Their lowest tier gives you 5GB of mail storage, but is only $1/m. You can add more storage if needed, or upgrade to a higher tier.