As someone who has used D3, I think you are vastly underestimating the audience of D3 users who would happily pay for a far easier solution ;)

(do agree with other comments that per-dev pricing is a bad model, though)

D3 takes ages to build graphs with. That's why NVD3 made such big news.

What you get when you buy a license is support. Which I remember was the main reason we had for not choosing NVD3 last time, and went with a library with much better documentation.

why is everyone these days so afraid of investing time? d3 is well worth the time invested learning!