Bought almost exactly that spec nearly 2 years ago, it had done 112k miles.
It's now done 155k miles and still drives like new.
Cambelt/water pump/tensioners need doing every 60k, so check they were done (see the servie history, not just the sellers word for it) and bank on spending about £350 to get them done again in 5-10k miles.
The engines are good for at least 250k miles so I would be encouraged that its a high mileage as it means mostly motorway which is kind to the mechanicals and you can benefit from a lower price. No idea why people are scared off by high mileage on Audi's, I would much rather have a newer car with high mileage than an older one with suspiciously low miles.
Check the climate control works properly, and it kicks out freezing cold air when on lo.
Not sure on the sport spec, think it included sports suspension.
Mine has the newer style wheels & crusie control (which is a real licence saver as well as a diesel saver).
If it's got the trip computer check the "2" setting to see what mpg it's getting. This might have been reset but worth a look, just blip the button on the wiper stalk (underneath) to scroll round 1 (trip), 2 (long term) and "off", then use the up/down buttons on the end of the stalk to scroll through mpg/duration/range etc.
Should be getting between 42-50mpg depending on type of mileage.
Wouldnt worry about mileage as its still got more life left than a brand new ford or vauxhall. There are not too many common faults on them, look for the obvious, excess exhaust smoke, they do puff a bit but to be fair you wont really be able to see any through your rear view mirror in daylight. Worn suspension will be given away by knocks from underneath, we were forever replacing suspension parts at less miles than this when i worked the main stealers. A really common and expensive fault is the instrument cluster, does it all work properly? Are all the pixels on the clock, odometer and DIS working?, this will cost you around £700 to replace if you cant find a good used one. Other than that nothing serious a few cooling issues such as water pumps are common as hell and are quite frankly a piece of ****, and coolant temp senders can play up. Just make sure before you buy the car insist on a 20 minute test drive and state that you want to take it out from cold, watch how she warms up, if its a diesel there quite slow to warm unless you get straight onto 60mph limits +. They take an age to warm in built up areas, a good 10 mins or so, when the car does actually get warm it should sit at 90oC and not move one iota, even in traffic jams 30million miles long as there designed in such a way that they stay consistently at 90oC. Hope this helps. As far as spec goes about the only standard things in sports are 17 5 star alloys, sports suspension, sports seats and 3 spoke steering wheel, 3 variants of exterior styling, it just depends on the person who bought it, they start with the bottom half of bumpers and side sills in unpainted condition, the next option was to have these areas colour coded, then there was the GmBh bodykit, which IMHO is the one to go for but i think will struggle to find one a little bit, but when you do they do command a bit more money, but definatley worth it as without they look pretty ordinary IMHO. Votex kits are even rarer again. Pretty much a similar kit to the GmBh but everything is abit deeper.