Check this video link from Daley Tech for a temporary sale code when ordering the Nolo VR from the website. This is the same guy who has put up many videos about mobile vr using psmove devices, as well as a few Nolo reviews.
Make sure to read the description!
Edit: they advertise support for the pimax 4k, as many are aware. This might just be the positional tracking solution we have been waiting for!