I have all my mailboxes with gandi.net. Each domain you buy from them comes with 2 fully managed emails, and I think 3GB storage each, for just over $1/month. I basically never get spam, nor blocked emails. They have 2 webmail interfaces too, but I don't use them. As a bonus, gandi financially supports a ton of open source projects, which never hurts.
I use https://mailbox.org/en/, it's from a small German company and I can use my own domain with the smallest plan for just 1 € per month. Their spam filter also seems pretty good.
> Few bucks a month add up and can be considered expensive by many.
I pay around 3$/month for Fastmail, I don't think it's expensive, an email address is the primary communication method everyone uses nowadays and it's useful every day.