It is expensive to replace the car key for newer model vehicles. Some dealerships charge $200 and up to replace a key. The expense is not from cutting the car key, which only costs a dollar or two in time and parts, but from programming the electronic chip in your vehicle's key. If you have a perfectly cut key without the programming for the chip, you can put it in the ignition and turn the car key but the car's engine will not start.
Automobile keys can wear out after years of use, and cutting a backup set of keys is a wise precaution. Most hardware stores will cut keys with a specialized machine, and this machine uses an automated process that can be manually completed by the average backyard mechanic in about 20 minutes.