Hey Sparky,
This one’s a bit off the wall. I’ve been digging for HMD hardware once in a while. Their often times expensive or big, or both! I’m still thinking of picking up one of the cheap ones from Ebay to hack and experiment with, but it’s not in the budget right now. Good luck finding a good set that’s a monocular, either. My personal want is a transparent display, but that’s really expensive 
I finally ran across mention that the core display hardware is available from Kopin.
http://www.kopin.com/cyberdisplay-module-products/
They build the parts AND they sell modules. Now, while they will deal with me for a single unit, I’m curious if there’s anyone else interested in this? At least I’m curious as to a deeper understanding of what resolution these things can actually do (for instance: CAN I do NTSC nonstandard to get the full VGA resolution?).
From Sparkfun’s standpoint: What’s the price breaks? I know the people interested in “wearables” are often willing to buy and hack displays from Wild Toys Spygear line, including the $140 “spy car” they have with a black and white IR camera and HMD monocle. There is a market out there, I just don’t know how big. The major issue I’ve seen with most setups is the sheer bulk of the design, but being able to start with the bare module, or module + interface board may draw more customers here.
I’d prefer a framebuffer/digital interface (their non-packaged driver chips and display boards support this), but other than the QVGA monocle (no driver chip) their prepackaged stuff is all composite. I wasn’t planning on asking Sparky to start doing optics for their component designs, either Although an SVGA HMD… nah, wallet hurts…
Overall, I’d probably end up most interested in the monocle (unless they have a VGA monocle) as then we could build the driver board to accept the types of signals we want, although the price is higher :-/