Darren
I bought mine from eBay. Can't remember the total price but was £150-£200 and took me less than an hour.
You'll just need someone with VCDS to code the Bluetooth to active.
Just checked (all off eBay)
VW UHV Premium Bluetooth 5N0035730D RNS 510 iPhone A2DP - 110 Euros delivered
Wiring Loom - 53 Euros Deliver
Microphone £14 delivered
So all in all around £160 for the kit then just my time to fit