https://mailbox.org
I pay 1 euro per month. With calendar, contacts, file storage and DAV. With aliases and your own domain. Plus it's a well-known company.
But mailbox.org is also priced per mailbox by default. When I checked with Mailbox.org support a few years ago, there was no way to go beyond 25 aliases on a single mailbox (even when one is willing to pay).