You can tunnel wireguard from a local server to a cheapie DO droplet for about 5$ USD/mo. Only one ipv4 pre dropte though. I read a blogpost that mentioned a free tier cloudflare service for public ips, but have not investigated.

At least where I am, the business class internet that I have access to doesn't come with static IPs and is approximately three times as expensive as residential for the same service level.

yes, a VPS would absolutely be cheaper. Even if you get the port unblocked, you're still not going to be able to set reverse DNS for spf records unless you have a business connection with static IPs. An IP alone will probably cost you the same as a VPS that will run a tunnel back you your home box.

In my experience, a business connection is usually twice the price and half the bandwidth.

Actually I just remembered, I can probably use my free Oracle OCI VM, not sure if they'd set up reverse DNS, though. Will have to file a ticket or search about it to learn more.

Disclaimer: Currently I work there, and it's true anyone can get a free VM "forever" (I've had one for 4 years).