What Nick and I are saying is there are a lot of people who really can't afford to operate a luxury vehicle yet buy an older A4/S4/A6/AllRoad simply because those cars have depreciated down to the same price as a Civic, 2.0L VW or Corolla. They look at it and thingk "why buy the econo shitbox when I can get a really nice/cool Audi/MB/BMW for the basically same price"? Unfortunately the Real Cost of Ownership is always maintenance which is something most people forget then find themselves shocked/scared as hell once the bills for that Audi/MB/BMW start rolling in... especially if they're comparing the RCO to that of the Civic, 2.0L VW or Corolla they're probably used to owning.
Just because a luxury car which originally cost $50,000 - $100,000 has depreciated to the point that it now sells for the same price as the econobox that started started off at $17,000 - $25,000 doesn't mean you're not still paying to maintain and operate a $50,000 - $100,000 luxury car. Most of the "OMGZ, older Audi's are sooooooo expensive to maintain/fix" comments that I've seen are invariably from people who bought without researching enough to learn that pretty obvious fact. Similarly most of the people going on about how unreliable older Audi's are are those people that thought they were buying a cheap car that you can scrimp or skip on maintenance without any negative effects. It's part of the reason why I make a point of mentioning the service costs in threads like this one.
People are always searching for bargains, as these cars age it's always going to increase because they're owned either by people who can't afford to maintain/repair them properly or by the original owners who have basically run them into the ground and aren't willing to put almost as much, or more, than the car is now worth into repairing it. Doesn't really change my previous statement about adult wallets vs wannabe boy racers buying cars like B5/B6 S4's and E46 M3's that they can't afford to maintain peroperly