If you are going to get a used VAG/Euro car in general I'd suggest.

A. Having a full service history
B. Buying privately, as private sales tend to less likely be lemons (but you have less to fall back on if anything does go wrong)
C. Look up common issues, such as the CDNA motor.. either taking into consideration that this WILL need a rebuild or that you can get it done by Audi Australia.. or just avoiding it
D. Get a pre purchase inspection if you can/aren't car minded
E. Find a good/reputable mechanic or work on it yourself.