Car radio codes are generally available for free. To obtain a car radio's code, record your vehicle identification number along with the radio's serial number, and then contact a local dealer or the car manufacturer directly. They can locate the information needed and give you the code.
You may need to remove the radio from the dashboard to obtain its serial number. If you are uncomfortable with removing and installing a car stereo, take the vehicle to a local dealer and have them reset the radio for you for a fee.
Other ways to obtain the car radio code for free include calling the car's previous owner if you bought the car from a private seller. If you bought the car from a dealership, you can try asking the dealership for the previous owner's contact information.