Locksmith: Some specialist automotive locksmiths may be able to create replacement keys for BMW vehicles, including programming the key's transponder chip
Online retailers: There are various online retailers that sell replacement keys for BMW vehicles. These retailers may have options for different key types, including standard, flip-key, and remote keys.
eBay: You can find various sellers offering BMW replacement keys on eBay. Be sure to verify the seller's reputation and check for compatibility with your vehicle.
Junkyards or Auto salvage yards: You can also try checking junkyards or auto salvage yards for a used key that may fit your BMW. Be aware that the key might require some programming to work with your car.
Contacting BMW Customer service: You can also try contacting BMW customer service directly to inquire about options for replacing your car key.