I got two quotes from two different sales people. They consider it an enterprise feature, so the minimum monthly is $3,000 for both — and that’s assuming only 50% PRO users want to pay for it.
Most Node.js apps (including this one) sit behind nginx. In any case, without a service like CloudFlare you’d have to manage the certificates yourself.
You could use Let’s Encrypt, for example, but there’s a 100 domain limit on each certificate. Things get complicated quickly with domains being added, changed, and removed all the time. You’d have to build an entire certificate management system and it needs to integrate tightly with nginx.
There’s a reason people pay for this
There are some other options that I’ll look into, though, it’s just not #1 on the list right now.