Your boundaries on cost make it tough, but aside from Tuta you might have a look at mail.ee which has very basic features (no E2EE for example) and a retro web UI, but very high storage limits. They offer free accounts too, and support SMTP/IMAP/POP3. It's Latvian-based so comes with the "100% GDPR compliance" feature if that's of interest.
Zoho.com is another that comes to mind. It's very feature-heavy/slick (you can tell they're attempting to market mainly to small businesses looking for a cheaper Google Workspace), has been around a long time and I've read positive comments from others about the service. It's an Indian company though so you don't get GDPR protections (or similar) as far as I know. The low-end plans are in your price range and I think they still offer a free plan - that's what I have anyway.
I've been a Fastmail customer for decades now and it's exactly what I want a mail service to be, but it's out of your price range and has no free tier.
It's annoying AF, much like the habit of people posting comments consisting of "Based" all over the place in recent times. The latter is dying down fortunately, and I hope the R meme meets a quick and painful death very soon.