I guess I just wouldn't have an open unauthed form and require a CC to use the free-tier. The contact-me form can just be a mailto: link and let the spammers go

I guess I just wouldn't have an open unauthed form and require a CC to use the free-tier. The contact-me form can just be a mailto: link and let the spammers go through the spam filter like everyone else. There are places where captchas is all you can really do but it's not like common use-cases don't have other options.