Cheaper alternatives to Mailgun

I'm working on setting up a mailing address for my website. I am able to use the default "postmaster@domain." to send outgoing with my gmail account, however for some reason I can't set up a custom email (one with my name), and I can't forward incoming emails to those addresses to my gmail account without upgrading.

I was wondering if anyone can recommend any (less expensive) alternatives to mailgun. Has anyone checked out https://forwardemail.net/en - it says it's totally free so I'm wondering if I should give that a try.