I bought a blank one from German ebay and had it cut by a local key cutter but he said not many people will be able to do it. That was the spare key though, programming will be dearer and has to be done by MINI.
Why bother. If you only want a spare your local BMW will be able to do a non remote one supplied cut and coded to VIN for under £20. We've had a couple and it is a 2 day turnaround and all you need to do is take the V5 and some ID.