$5 / month is still pretty close to $0 / month for many people. I transitioned from Gmail -> Fastmail a year ago, and I'm very happy with all aspects (reliability, features etc). Would be fine with paying > $5 month if that's what it took.
It's quite disappointing how skewed our perspective on software pricing is. I grew up in an era when compilers cost $1000; now people complain about $3 for an iPhone game.
Given that a burger cost $5, I'm more than fine with sacrificing a burger each month for private email.