As we know, it is much expensive to matching keys in 4s shop than that of garage or locksmith. However, do you know why?
Actually, it is for their complex procedure and profession. When 4s shop gets car owners information which will be sent for manufacturer to inquire matching IMMO codes and feedback to 4s shop. Then 4s shop starts to create and modify vehicle computer and lost data.
As to garage or locksmith, car key programmer is used to read pin code and program keys for you. Most of the tools they used are cracked version.
There is one thing in common that lost keys are disabled, while it can open car door both for 4s shop or for garage with auto key programmer like BMW Multi Tool. You could change your mechanical lock to avoid thief, or no leaving propriety in the car.