I sometimes wonder if I should set up email with custom domain, but then I read how it will be quickly blacklisted by everyone and your mail simply won't be reaching anyone. That is the biggest problem I think, not the domain payments.
I've been hosting my own email for about 10 years now. I started using it just for throwaway accounts and I've been ramping up usage slowly ever since. By the time GMail blocked my account with no explanation I had a fully-functioning domain with good reputation ready to go.
You really don’t want to be self-hosting your own email in 2023 and all the headaches that entails anyway.
Use a reputable email hosting service with your domain, problem solved.