Perfect solution? It works like it was custom-built for my site, is as easy and predictable to implement as Persona's `get()` API, and of course has excellent security, privacy, and operations.

I would have been willing to pay for such a thing had it existed when I started. It would have needed to be proven, though, because I worry about longevity. The exact price isn't so important, within reason; say, less than $100/mo. At the higher end of that range, I'd expect it to have some serious word-of-mouth gushing.