Local dealer or any OEM parts house (Max BMW, etc) will have blanks.
Any locksmith shop or local BMW dealer should be capable of cutting the blank.
Current: 93 R100GS, 03 XR650R
Prior: 73 CB350, 77 R100/7, 83 R100RT, 04 XR650L
I love every motorcycle I've owned and even some that I haven't.