depends on:
1, the build date, i would stay away from anything build before 01/06 to avoid early build 06.
2, history of the car, get the service history to see if the car's been problematic and if the recalls are done.
3, paint condition, scratches and did it ever have any panels repainted, if so was it fixed right?
4, interior condition, how is the leather, any rips or scratches?
5, how does it drive?
6, how long is the warrenty good for?
without seeing the car, its hard to say. If the car is mint 33k with extended warrenty is pretty reasonable.