keys for all bikes with BMW immobilisers (R1200, K1200, F650/800) are only available from dealers. There is a maximum of 10 keys available for each bike during its lifetime. If you loose all 10 keys, you need a new ECU.
To put this in perspective, Honda's HISS equipped BIKES may only have 3 keys available before requiring a replacement ECU?
Oilheads & G-series keys can be recut cheaply by a locksmith.