BTW..if you don't really need a remote key because you are only looking for a spare/back-up key...check to see if you fall within the build dates of a non-remote key. That will save you some money right there because it's the remote keys that cost the most. The non remote keys usually can be had for between $50-$100 (depending on which one you get or is available for your model year).
Up to 10/2003 build date...you can order the non remote keys #1-#3...again, all of these keys are usually less than $100:
There are some areas where people have invested in the Chinese equipment that can write the ISN (individual serial number) to a blank EWS transponder...but you better know what they need to do so that you can verify that they know what they need to do...if not...you'll have spent money on a key that may fit your ignition, and may have the electronics inside to program FZV & DWA (central locking & anti-theft alarm siren systems)...but will not have the ISN to communicate with EWS system...thus the car won't start.
Again, there are some areas of the country where you may find a 3rd party person that is not unscrupulous..and know what they're doing. If not, just go to the local BMW dealer as mentioned above...with proof of ownership and ID...and they will order a key for you that will come in already cut and programmed to your EWS system (based on your VIN...which you will need to give them as well).
If the dealer won't program the FZV/DWA remote features for free...see the instructions below that are posted almost weekly: