If it was a dealer and they required the VIN, then it may have been cut already. Mine cost $260 from my dealership. And I know who you mean by remotes for less. I also had to return mine as we couldn't do anything with it.
So dusting off my experimental notes, if you buy a "spare" key off eBay from someone who found it in their drawer after they sold their Rover, even if you replace the key blank, you will not be able to pair it to your vehicle because it has the seed for the wrong VIN # implanted.
If you buy a "blank" from another source (there are lots originating from China), it seems there are some who claim it can be paired to your vehicle, which I am skeptical of - I don't know of a US Land Rover dealership who can do any of this in house - they have to order the keys from the factory in the UK and provide a VIN # for the order, which I believe is part of the seeding process to allow your new key to be paired. I vaguely remember coming across some non LR description of the cryptography handshaking going on - the key has to trust the vehicle and the vehicle has to trust the key. The latter is achieved with the "pairing" - without the former, the latter fails. My theory is that LR UK keeps something akin to the private key for each VIN which they blow into the fob so the vehicle agrees a match with the same private key that is squirreled away somewhere in the immobilizer circuitry.
If you look at the circuit board you'll see it appears there is a one time program RFID chip - I have a Chinese RFID key reader sitting on my bench waiting for me to get some spare time to Experiment for Science. They also use the VIN # to lookup the pattern for their key cutter which is I am told, akin to a CNC machine. Maybe that's where the Legend of the Uncuttable Key came from.
By the way, my locksmith was able to make his copy without removing the blank from the fob. Maybe I got lucky and this old guy knew some dodges that others didn’t
Long story short, yes I handed over $260 to my LR dealer but declined their kind offer of $120 programming fee. What they wanted to charge me an hour for, took about five minutes with my kit. When I mentioned it to my service advisor his comeback was that their equipment takes at least twenty minutes to set up and they have slow laptops. I've seen the software and I grant you it's slow as molasses and you probably should attach the LR to a battery maintainer when doing any programming work, but that still smacks to me of a restaurant wanting to charge you for the time it takes to lay the table and wash the flatware by adding a surcharge to your steak dinner. Oh wait maybe they do....
I need a beer now....