As much as I love making electrostatic headphones, I don't think that I will ever make them for money. I'm just too busy with my work, and I really prefer sharing my knowledge and encouraging people to try to build them by themselves. I am willing to share everything of my design with everyone. Just let me know if you're interested to build.
By the way, making a pair of good sounding electrostatic headphones isn't that difficult, but to make them as efficient as Stax headphones is not so easy. Until MrSpeakers and Phenomenon can make their phones to sound as loud as Stax, I would say that they still have a lot to learn.