So my 2c.

I found a local locksmith who was able to mechanically copy my original key onto a blank using what I think was also called a sidewinder machine. It worked the locks and the ignition. Of course it did not disarm the alarm nor get past the immobilizer.

I tried a couple of sources of "unprogrammed" keys on eBay and neither I nor my local LR dealership were able to pair them to my LR3. There appears to be a two part system to the actual fob. It has to be pre-seeded with a code based around the VIN number of your LR - this is why it has to come from Land Rover in UK. They can also CNC cut the key again based on the VIN records. Once you have the key with the seed value in the embedded RFC chip, you have to "pair" it with your vehicle much like one does with a bluetooth accessory. This CAN be done with third party tools like IID, Nanocom, Faultmate; takes all of about five minutes and can save you $100 at your dealer. Note that you have to have at least one existing working key to do this.

The only other option I think is available might be to clone an existing key fob - there are supposed to be tools that can read the RFC seed and write them into a blank. However, if you have seat memory controls then they are going to be fooled into the same settings as it is a clone. I did briefly experiment with trying to read the RFC codes with some kit from China but lost interest as the ROI wasn't there.

YMMV.