There are two main types of filing cabinets, vertical and lateral files.
Vertical files are the more traditional type, with a number of drawers ranging from two to ten, designed for a single file to fit vertically in the width. These cabinets can be quite deep, but take up very little width on a wall, as they are only the width of a single file. The are usually just over 1 foot wide (30 cm), and may be anywhere from 12 to 30 inches deep (30 to 76cm).
Lateral filing cabinets, by contrast, are designed for use where wall space is less important, but depth is an issue. These cabinets are much wider than vertical files, allowing them to hold documents of much greater width as well as files ranging in width. Such cabinets are not very deep, often less than 1 foot (30 cm), but may be up to 45 inches wide (114 cm).
Within both types of filing cabinets, there is a range of quality. One of the most important aspects of a filing system is its suspension. Many inexpensive cabinets have flimsy suspensions and, once laden with files, the drawers may be difficult to open and shut, and may often stick. Another important aspect of quality is the durability of the cabinet itself. Good ones are made of reinforced steel, ensuring the protection of the files. Many mid-range to high-end filing cabinets have counterweighted drawers, helping to ensure that the cabinet never tips over, even when multiple high-level drawers are pulled out.
As with many safes, filing cabinets may also be outfitted with fire-resistant features. Those certified by the Underwriters Laboratory are tested to sustain temperatures of 1,700°F (926°C) for a full hour without the internal temperature ever exceeding 350°F (176°C). Ones rated to protect fragile media such as disks and tape from fire will withstand scorching heats without the internal temperature exceeding 125°F (52°C).
Filing cabinets cost anywhere from $30 to $2,000 US Dollars, depending on quality, type and size. Expect a fire-resistant, high-capacity, locking lateral file to cost quite a bit, and look to smaller vertical files without any frills to stay on a budget. In the end, there is a large enough range of options available that most people are certain to find one with exactly the features he or she looking for, without any extraneous add-ons, for a reasonable price.