I only had one key with my GTI but I got my second spare key done for around £60. This is what I did for mine:
- Bought Blank VW Key Shell with unused HAA Blade - £4
- Got second hand genuine VW keyfob with matching electrics. (I took the electric board out and put it in the new shell, the rest was scrapped) - £7
- Bought new ID48 transponder chip - £4
- Had key blade cut by local locksmiths - £15
- Had the key programmed by my local VW independent specialist (they got the tools like VAG Commander for immobilizer and VCDS for remote programming) - £30
In the end I got a fully working spare key for a fraction of what the main dealers wanted, plus it gives me peace of mind that I have a least a spare should I lose mine.