Carmack said they had a lot of internal discussions about that but they decided not to do it for whatever reason.
You should probably just get a Rift with the bases. I got mine for around 350.
I have one; I just find the tracking pretty fragile. I often need to set it up again on a weekly basis.
This really makes me happy I went for a Vive. I stuck the lighthouses up near the ceiling, calibrated once, and it still works perfectly eight months later. And no USB cables.
Hopefully they perfect inside-out tracking eventually but in the meantime the lighthouse system just works for me.
Can I tether it to a PC if I want to? My primary use case is PC gaming.