There are a range of lights available which are specially designed for reading. Some are free-standing lamps designed for use in living rooms and offices. More commonly, though, book lights are portable devices designed specifically for using in bed without disturbing a sleeping partner.
When choosing a free-standing light, there are several points to look for. If you often share a room with others, you will want a book light with a very focused beam so that you do not waste any light. You may wish to consider a light with a flexible stand, particularly if you often change position in your seat, or if people of differing heights will be using the light. It can be worth paying extra for a dimmer model so that you get the brightness you need at any particular moment without wasting power. And if you are likely to be sitting quite close to the light, look for a model which is advertised as running at a cooler temperature.
With a book light designed for bedroom reading, you have a couple of options with price. One is to take the attitude that there are many models which are so cheap you can afford to try a few without too much research until you find one which works for you. Another is to decide that it is worth paying extra for a good quality model as it may work out better value in the long run.
There are several different ways for a portable book light to be positioned. One of the most common is in the form of a model which clips to the top of the book. This can be useful, but can also be annoying if you have to unclip it every time you turn the page. To get around this problem, you may want to get a model which clips vertically along a book cover or spine.
Remember that the price of a book light can be outweighed by the running costs. There are two points which you need to check. First, find out how long the battery life is, being sure to check if the light uses common batteries or rarer and more expensive ones. Second, check the lifetime on the LED bulb or bulbs used to provide the light. Many modern bulbs will last so long that most users will never need to replace them, so it’s not always worthwhile to go for a cheaper model where the bulbs will wear out quickly.