-
Good mechanic. Spares are not too bad. Just pick the right car. My old A6 has the 1.9tdi engine. My mechanic bought it from me. I think there are around 250000 miles on it. Obviously a few issues - bodywork on front wings as always. New turbo fitted at 210000 miles. Various other bits but they can be sourced from a breaker to save money. If you get a good one, it should be no more expensive than anything else. It might be cheaper as parts are reasonably plentiful.
I miss my old car!
I'd be tempted by a cheap TDI A4 Avant but you could easily spend what you paid for it on parts and labour when it breaks.