If it is a one sided key, you can cut it.
But as far as i am aware, from E34 onwards the keys must be ordered - they are cut from code by laser. They cannot program radio transmitters or alarm buttons at the dealership, it must be done at a BMW head office (in my case this is Singapore)
I need to get a pair of keys (plus the little light units) which will cost me $40AU each including postage.
Expensive but you have no option
eBay is cheaper for those light units, coming in at half the BMW price!