I’ve been running my own mail server using Mail-in-a-box on a digitalocean VPS for about 10 years. I also pay for an external SMTP relay service because I still get randomly blocked by Google/Microsoft/whatever just by virtue of having a digitalocean IP.
Total cost is $15/mo for the VPS and $50/yr for the relay service.
I’ve been running my own mail server since ~2002. For many years I was using qmail, of all things, on a home ISP connection. I wrote a semi-popular guide on adding spamassassin support to qmail. I was a true believer!
When hosting email from consumer internet became untenable, I migrated to digitalocean and Mail-in-a-box. To be honest, it’s worth the $15 to have a 100% always-on device hosting the email. I host lots of other stuff at home and having email be a separate thing makes it much easier.