I would actually disagree- it doesn’t take much budget at all, or even a quality server setup, to have a decent uptime. A consumer router with a sim card slot is possibly something you already have. If not, a cell modem can be as cheap as $30. You could stick your email server on a old shitty raspberry pi. A data sim is $6/mo. If all you’re running is a cable modem, a router, and a rpi, you don’t even need a big fancy UPS, you can just get a DC battery UPS for like $40. It doesn’t need a lot of budget, quality stuff, or even a ton of hours in the week for self hosting- once you get this stuff set up it should stay working other than the standard upgrades/maint your email server will need.

Everything past that, like setting things up so your mail server is reachable on two IP addresses, is just… skill.