As mentioned above, it will have quite a bit to do with driving conditions, etc... also, there is not typically enough room left on rotors to have them "turned", so the rotors should be replaced with the pads anyhow. If you start hearing a metal to metal sound when braking, it is likely the backing plate hitting the rotor.
We do have a selection of rotors and pads avialable when the time comes to have things replaced that can be found here on the website for 1.8T models:
Volkswagen New Beetle 1.8T > Braking > OEM
The RPS Kits are usually the best deal as they include rotors, pads and sensors with free shipping to the lower 48.
