The main key with the transponder is £50 you will need to supply them with your key, I think they flash your key and copy the details on to the new key...part# is 1T0 837 246
There is 4 different lower halfs to the key transmitter mainly cos they have different frequencies but they cost around £45 and the main part# is 1K0 959 753 then either G, J, K, or M. The dealer will order the right one from your chassis number/reg number,
Darren