Seems to be some scare mongering going on here, Iv just hit 52K and I got the car at just under 20K.
The pricing above is about right if your going to Audi, I used Audi for everything until my 5 year warranty ran out but due to the fact you are looking at a 60K miles car id imaging you would be happy with taking the car to Indi's? Do you have any good ones local?
I use a very good indi, New uprated discs and pads all round sub £500. Full major Service about £350. Haldex I do myself every 10K £45. Running costs (Fuel isnt the best but then again its a 300bhp 4x4) is comparable to a normal A3 or 1 series, its just the repairs are a little scarier for anything major, i.e engine / gearbox
Only problem I have had is the common water pump failure but that should have shown its head by 60K and if the car has decent enough SH it should be documented , I have aftermarket warranty and that pump / stat housing was covered, I would recommend a full wear and tear warranty especially if you have S Tronic and to cover the miss fire concern just in case to give peace of mind, but make sure the terms and conditions are bullet proof.
Mine is lowered (has been for about 15K miles) and no wishbone issues or damper leaks but I have heard of those being fairy common, but parts are cheap enough (Same parts as an A3) and the dampers aint too pricy if it doesnt have the Electronic dampers.
Only other point is check for Whines on the rear diff. could be on its way out if so, but again a used low mileage diff isnt the end of the world.
I would say all of the above would be mentioned in the Service history, i.e Water pump change, recalls, S tronic service at 38K, if not then be careful.