With more traffic, any VPS will be the cheapest, eg Digitalocean or especially Hetzner. You don't need to have MongoDB there, as you can host it separately, e.g. on MongoDB Atlas which has a free tier. And of course there's Payload Cloud which is quite a good deal - especially if you compare it to the crazy prices of other CMS' cloud offerings. Obviously won't be as cheap as managing a VPS by yourself though, but it has other benefits.
Never actually tried Netlify myself so I can't comment on that