I want to share my FPV setup I built on a small budget which uses some Virtual I/O iGlasses made in 1995. I bought these in 2001 for about ~$75 and they are 600x800 in resolution and 120htz (60htz per eye). They are capable of displaying 3D video too. The 3D effect requires a video multiplexor, and while this has some neat applications for UAVs, I won't talk about that here. The goggles were originally pretty expensive and universities used them for VR caves and the military used them as well. They use a prism so you can actually see through them, I personally think this is somewhat preferable to the Oculus Rift head-in-a-box approach. I admit on bright days you may need a dark bag anyway. These were originally sold with an optional head-tracking unit as well.
The iGlasses use a barrel jack that is connected to an AC/DC adapter which provides 6v DC power. I disconnected this and soldered on a USB cord I had lying around. This way I can use an inexpensive USB power supply and make them portable. The USB power supplies typically run about $5-10 dollars and the CR18650 lithium cells can be found for a couple dollars each or even for free when re-purposed from old laptop batteries. If the 4500mAh rating can be believed then I have 18Ah of power for each little USB black box. The video RX pulls more power than the iGlasses. I'm not sure how long it will run, but far longer than my quad. I've run an rPi for nearly 24hrs. Another nice feature is that they can charge in a daisy chain, so I can charge several and even a GoPro at the end of the series with only one charger.
The iGlasses are hit and miss on eBay. Often they don't come with a cord or the head-phones are broken. Some people think they're still worth the $1,500 they paid in 1995. Still, they frequently go for $20-80 (and by writing this I may affect the existing near zero demand). I have flown with the headphones and they provide some information on intermittently windy days, but for the most part all you can hear is the props. The headphones are not really necessary. The company that makes them went out of business, but I suspect some of the video glasses for sale from China are direct descendants, derivatives of very nearly the same technology. I have been watching them for years and some of the same selling points crop up in the new sales literature. These iGlasses were supposed to be like watching an 80" TV from x number of feet away which occasionally shows up in the video glasses listings on eBay (the silver ones with a red-Jordi-style-visor. There are still cheaper versions which I doubt perform as well as these do, as well as nicer ones too.
The cord is not crucial either as the iGlasses use the same header pins most of us are already accustomed to working with for servos and flight controllers, etc. If you look at my setup above the cords are probably the heaviest part. I haven't started to make my own cable yet, but I'll share the pinout I stumbled on some time ago.
These goggles are pushing 20 years old. They're not HD, but for the analogue stuff most of us are using they're great. They're not super bright either so I typically have to fly standing in the shade when there is full sun. I made a cardboard visor which helps and when the iGlasses were mint they came with a similar piece of plastic for the same purpose. They work great in the evening. I personally haven't tried any fatshark products, but a friend who has said he liked my setup better than his goggles. The resolution is adequate for most, I believe; it allows for good compositions for photography and FPV flying.