Union pre-cut mortice
You can get a union pre-cut mortice key from different sources and even online. Prices are at around £5 on average but can also go upwards of £8. The cost really depends on the key-cutting shop that you choose. Big-named shops can be more pricey. If you want a less pricey key-cutter, look for a local shop.
Yale Patented cylinder key
These patented keys have been on the market since 2018. They are more expensive to buy wholesale than regular, non patented keys.
If you are unsure if yours is patented, take a close look at each side of your key. It will say patented in small writing around or under the head. Most key cutters will still be able to cut these but they will cost more.