I quite often go hiking in the evening after work and I have a good head torch but sometimes I wish I had some night vision goggles because often a headtorch will scare wildlife and cause farm animals to go crazy (not so good if you are on a footpath going through a field). Ideally I would like some that were not heavy and don't move around a lot when I walk. This may not exist (From google searches I've seen there are cheap ones from china that look like they don't work, ones for hunting that you cant really walk in and very expensive military grade ones).
There are 3 main types of night vision equipment;
This is the type most commonly used by the military. It works by effectively amplifying the available light and may work in visible or IR spectrum or both and works in a similar way to a TV camera. These systems rely on some light e.g. from stars or moon being available and won't work in total darkness. In a military context they have the advantage that they are passive and as such difficult to detect with similar equipment.
Active Night Vision
This works by using a source of infra red illumination which is close to but outside the range of human vision which can be detected by a sensor similar to a digital video camera this has the advantage of providing better resolution than passive systems but is detectable to other nigh vision users.
This detects the longer wavelength IR emitted by warm or hot objects such as people, animals and vehicles, it is however much less useful for general navigation.
All night vision equipment is by its nature somewhat heavy and bulky, although each generation has seen smaller and lighter units even the most sophisticated ones are somewhat cumbersome and the latest technology will, of course be the most expensive. Similarly military units are usually worn with helmets which offsets their awkwardness somewhat as they have a stable mounting platform which can counterbalance them to some extent.
Another disadvantage is that, like all optical devices, they can narrow your field of vision and distort depth perception which somewhat offsets their benefits in navigating at night, especially over uneven ground. For example try walking around just looking through the viewfinder of a camera, it is not easy.
Even in military context NV would not necessarily be used for just covering ground at night.
An alternative is to use a torch with a red filter or red LEDs this reduces the overall brightness and tends to be much less noticeable at a distance and is less disruptive to your own night vision.
It is also possible that wildlife is more bothered by the erratic movement of the light source than the light itself so you might be better off with something which produces a diffuse omnidirectional glow than a tight beam headtorch.
If you give your night vision time to adapt it is rare that it is too dark to navigate at all and even when it is all you need is a bit of a diffuse glow to help you see where you are putting your feet and any obstacles coming up. In fact a very gentle light source is often more useful than something very bright which ruins your night vision.
So it may in fact be the case that what you really need is less light not more. From a more philosophical perspective you may find that walking in darkness brings your other sense more into play and you get a different perspective on your environment and forces you to be more aware or your surroundings rather than being constrained to a narrow field of artificial illumination. This will also make you more aware of the noise that you are making and in turn reduce the disturbance you cause to wildlife.
Define affordable? With a mirrorless full frame camera and a f/1.8 or better lens you can literally see at night (f/1.4 or better on a crop sensor):
Hold your eye up to the electronic view finder and walk around with it. This works because the human pupil diameter is only as big as 3 to 8mm, but your camera lens can be as big as you need it to be. The best lens for this will be a 35mm prime to match the natural focal length of the eye. Use a longer lens, if you want to scan the horizon for animals in the distance instead of walking around with it like night vision googles.