I solved this problem with a smaller HMD and 3 axis head tracker. 2 camera 'robot head' with 2 mini mics mounted, 2 Tx, 2 Rx, Awwww Yeah! Works like a champ. I sell it for $1100, which is cheap if you add up all the tech and what not. I'm definitely not doing it for grand profit margins. I just love 3D FPV! Here's the usual shpeal I put on forums:
We, here at FullSpectrum FPV, have created the world's first fully featured 3D fpv system. With an in house built dual input Head Mounted Display and a dual camera/ dual transmitter 'robot head', we've built a system from the ground up that utilizes the most tech for the highest resolution and frame rate possible!
Previous forums about modifying two standard fpv goggles into one seems wasteful (do the left over parts get thrown away?), and most virtual reality goggles on the market that allow 2 video inputs start at 4 times the cost of our entire system. Oh yeah, and the other 3D system at NGhobbies.com sure seems lacking to us. 1/4" cmos sensors? Single transmitter image interlacing? Come on, we can do better than that! We've come up with a way of using small 8" LCD panels in a way to create a 3D viewing system. Our product contains all you need for 3D FPV! Plus it uses a NO DRIFT 3 AXIS Head Tracker for total Realism. Great for turning into a turn in a car or correcting tilt during flying with ailerons!