Although the ideal scenario when buying a used car is to have two factory keys, just having one key should not necessarily mean you should rule a car out. Depending on the exact model of vehicle, automotive locksmiths can provide and code duplicate keys, and in some cases deactivate any other keys, so you can be sure that the keys in your possession are the only ones that can be used with the vehicle. An automotive locksmith will also likely be able to provide this service more cheaply than a main dealer.