what exactly is the question here? i have one and know a few other people in the area with one.

if you plan on buying one put aside 1500-3000 for repairs.

it also depends A LOT on what year car you get and how many miles is on that particular car.

"older" S4's have a Bi-turbo V6 which isn't cheap to fix and newer S4's come with a 4.2 liter V8 which won't be cheap to fix if it breaks.

There are many items on these cars that are known problems and should be addressed as soon as possible. If you are serious about getting one i'll start listing these items.