Definitely the cheapest way to one key. Just make sure to have it done by a locksmith or a good hardware store. Obviously the machine at Walmart that cuts both sides at the same time won't do it. My local locksmith only charges $2 a copy and his keys always work well.

 

Ok, gonna put in my 2 cents here. To remove the door lock, you do not do it from inside the door. The clip that holds the door lock is accessible from the door edge. Pull clip and door lock is released from the door. pay close attention to the direction of the cam, and how it is attached to the locking rod, as they can be put in wrong at reassembly.

The door lock has a sheet metal cap that is peened at both ends. You can carefully remove it to access pins and springs. The Ford 5 pin key system only has 5 different depths. Springs do not matter, but top and bottom pins go together. Take them out one cell at a time. Use patience, if you don't have any, don't do this.

Other reasons for keys not working. Look at your key, if the valleys and peeks are nicely rounded, your key is worn and might not be hitting the pins in the door lock properly. The key is used in the ignition more frequently than the door locks and will wear with the ignition. A locksmith should be able to decode your key and make you an original. Another possibility is lack of use of the door locks has caused something to get gunked up. Spray it with a good penetrating fluid and run your key in and out several times, repeat several times. If this does work, after getting it freed, clean with carb cleaner and lubricate with a good lube such as graphite or triflow.