Mateo,
Hmmmm...a bit of a lottery.
I have an S2 (the little brother) and aside from a full head rebuild and turbo rebuild at 125K and more bore wear at 150K which will require an engine rebuild and rebore...
they are great...
Seriously tho... if you are thinking in that mileage range budget for a full engine rebuild and gearbox rebuild.. its 2.3 engine afterall... getting 315bhp out of it is a tall order, even the 230 standard is good for the age.
In other terms such as the body work, interior fittings etc they are exceptionally good...electrics work aside from the back lit OAT guage on the dash, you do get brake accumulator failures ( a bit like Wayne's 959 accumulators) and its a pain to get new ones (and expensive). But essential.. if you have a duff one and you stall at speed you will have no brakes and be wrestling with a ton and a half gorilla (BTDT).
On the other hand overall they can be great cars.. sleepers in every sense of the word, as nobody, but nobody expects an older Audi wagon to be as quick.. even in the S2 the odd P-car is easily surprised...I believe mine is not standard so there is a big step as the turbo kicks in, its even larger on the RS2, but certain companies can provide remaps which raise power (380bhp for the RS2) and reduce the turbo lag...they really do reprogramme the ECU, not a increase max boost jobbie...
The down side is that the engine is way out there in front of the front axle line, its nose heavy machine and whilst very fast its not one to be taken down the UK country B roads for a fun drive.. simply not what its there for.. however on some of the wide open A road sweepers in Scotland its in its element...very very fast and once it gets damp or muddy there is practically nothing (new C4s excepted) that can keep up.. even motor bikes give way....(apparently
)
So an overall budget of say £20K (10-13K purchase with a 6k float; engine rebuild is 4K, plus bits an pieces) and you will have a stunning unobtrusive fast car that gets far less abuse than a Pepperwagon....and if you do get it remapped then its possibly faster too....
PM if you want.