As I mentioned in my introduction, I'm a bit obsessed with obscure, rare HMDs, so I'm posting my reviews of what I've collected so far.
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The Virtual Research Flight Helmet
I'm going to start off with the most recent, and rare addition to my collection, the Virtual Research Flight Helmet. This HMD was one of a handful of HMDs released in the late 80's and early 90's to use the legendary LEEP optics, which not only provided a huge field of view (around 120°), but also warped the visuals in such a way that it actually helped the standard low resolution displays of the time seem more high res; by condensing the pixels in the general area that your eyes are the most focused (See the example below).
The Flight Helmet is a real beast of an HMD, and to some it may look a bit scary, but it's actually very comfortable, this is due to the very effective adjustment knob on the back, not to mention the overall balance of the unit is great, so the weight is never resting on one single portion of your head.
Now to the best part of the HMD, the optics. As I mentioned above, these are the famous LEEP ARV-1 optics. The display resolution is quite low, but the amazing optics combined with it being stereoscopic really helps hide this, you really do get a great sense of motion and immersion from having an image that covers a big portion of your peripheral vision.
The conclusion: The Flight Helmet is a great piece of VR history, and despite the very low resolution, it manages to give you a great immersive experience (You're not buying something like this to read text anyway). The only downside is that you need two NTSC to VGA converter boxes that allow you to offset the screens, this is because the large LCD panels inside the HMD don't match the distance between your eyes correctly, a flaw that almost all LEEP based HMDs had.
I give the Flight Helmet a 9 out of 10.
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The Virtual Research VR-4
Here is yet another amazing HMD from Virtual Research, it is often compared to the Visette 2 by Virtuality, but higher quality (although a bit less durable). I would say that this is probably the most well designed HMD that I've ever used; virtually every part of it is adjustable, and it's about as comfortable as they come without sacrificing the visual quality. The optics in the VR-4 are very high quality glass lenses that provide a solid 60° field of view. The display resolution is about the equivalent of 640x480, which may not sound like a lot, but this combined with the great optical quality gives you a very crisp stereo image.
The conclusion: I can't really think of much else to say about the VR-4, this HMD is pretty much flawless; it offers a great balance between resolution and field of view.
I give the VR-4 a 10 out of 10.
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The Liquid Image MRG2.2
I have mixed feelings about this front-heavy, boxy cyclops of an HMD. One of the first things you'll notice about it is the durability, this thing is probably bullet proof (not that you'd want to test that!). The second two things you'll notice is that it's Monoscopic, and it has an 80° field of view. Now that FOV sounds pretty good, but you'll discover quickly why quality optics really matter.
As you can see here, the optics are really nothing more than a modified desktop magnifier, which is actually pretty cool in some ways, but compared to the other HMDs I've used, it really doesn't hold up well. The optics don't distance the image enough, causing it to feel pretty close to your eyes; this combined with it's low resolution results in blurriness.
The conclusion: Although my review was harsh, I actually really like this HMD in some ways, it's all made with tools and parts that you could actually go out and buy yourself, making it like a homebrew HMD. You could actually upgrade the LCD panel in this to something with a higher resolution, and probably get much better experience.
I give the MRG2.2 a 7 out of 10.
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The Phillips Scuba
Last, and definitely least is the Scuba:
Now I'm going to try not to let nostalgia get in the way with this one, it was the first HMD I've ever owned. I like the way this one looks, but that's really about it for this monoscopic HMD... Now for the time, this actually had a nice FOV for a consumer HMD (I would guess around 40°), but the optics are chunky and low quality, making the already -very- low res display seem even worse.
The IPD (inner pupillary distance) feels quite a bit off, and the "IPD adjustment" knob on the bottom of the unit seems pretty much useless, simply causing the optics to rotate slightly, so your eyes never can really focus, which quickly causes some nasty eyestrain.
The conclusion: There has always been a shortage of high quality consumer HMDs, but this one is exceptionally bad. I really could never find much to like about this HMD, especially since far superior HMDs existed around the time it was released, like the VFX1.
I give the Phillips Scuba a 2 out of 10. (1 point for looks)
Thanks again.
So it looks like the minimum would be the V6 and thats $950 but doesnt sound like it can take inputs greater than 640x480 so another deal breaker 
