I got my key myself done for under £30 with pairing.
The key is in 2 parts, the chip which is in the key half, and the remote control.
I bought the correct remote control for around £15 and a blank chip for £11. Both off ebay.
Got the key cut for a few quid, put it all together, and used vcds to program it.
Once the chip is used, it cannot be used on another car, so you would need a blank one.