Pretty sure you got your stock master cylinder that came with your car from the factory. The reason why you can not find this part number is that because it's the part number just for the master cylinder, but according to BMW catalog you can only order master cylinder+seal ring+nuts. This package has a different part number from what is printed on the master cylinder.
Go on ebay.com and look for a master cylinder for your car. All of them are going to have a sticker with the same part numbers that you listed.