IMO, a good price for a great car. Yes Mondeo's etc are cheaper to service and buy bits for, but thats because you have to buy more bits for them over their lifetime.
Yep, the autobox can be problematic but thats usually the 6spd box as opposed to the 5. (so i'm told and understand).
Wishbones are a 'common' issue too as the audi is a heavy car with a heavy engine, but, its cheaper to buy a new item and fit it then the hassle of new bushes, my mate just had his 2.7t done at around £30 a side for the parts.
If you have access to vagcom/diagnostics, take it along and use it to bargain on the car if anything comes up. (under the dash, drivers side, a purple plug)
Why are you still in front of your computer and not looking around the car
Excellent car, excellent spec, excellent engine and just all round excellence.
Oh, find out what he's been towing with it too - I am always wary of cars with a towbar.
It should feel a very solid, well built car, great sound system, comfy seats and a strong engine, it should handle well despite it being a big car. Doesnt say whether its quattro or not, that would be a bonus if it is.
Good luck
jt