There are several different types of map reading light available on the market that all have widely varying uses. There are map lights intended for use inside your car to allow your passenger to look at a map easily at night without disrupting the driver, and there are also lights used primarily by amateur astronomers which allow them to look at star charts and other maps without forcing their eyes to readjust to the darkness after they have looked at the map. Obviously, this type of light could have many other applications as well.
There are a lot of really good reasons to buy a map reading light. Whilst traveling it will make it much easier for you to follow directions in low light. Usually it would require you to turn on the lights in the car for a short period of time. This is not only obnoxious to the driver, but could also be extremely dangerous. Especially if they have trouble adjusting to low light conditions. If you are going to buy a map reading light it is a much better idea to look online than it is to try and buy them from a local brick and mortar store. When you are looking for a product online you will have significantly more choices which makes it a lot easier to find your ideal map reading light, and this also makes it much easier to find your ideal map reading light within your budget. Online stores have the ability to offer things at a significantly lower cost than most stores for many different reasons. They have fewer middle men and aren't required to keep products in stock at many different locations and can instead just have them at a single place. This works out for you because not only can you get a lower base cost, but you can also find map reading lights significantly on sale, because the manufacture is encouraging online sales. It saves you money and makes them more money, its one of the greatest win-wins in business today.
There are a few types of map reading light you could consider getting. The first kind is intended for automotive use only. This map reading light usually has a fairly long flexible metal arm with some LEDs at one end and a cigarette lighter port at the other. I find them to have a very clean design and work perfectly for automotive use. There are also similar lights which can be attached to the interior of the glove box but require you to hard wire into the car. They are also very useful but hardwiring them to the car can be a project that is beyond the average persons experience.
The last kind of map reading light, is simply a reading light like you would buy for reading a book. These can easily be used for maps, but you often need to look for a light that is smaller than you would accept in your home. They need to be transported much more often after all. They also have the advantage of attaching onto the map itself and can be used outside of the car.