Having worked for Audi, make sure you check out the gearbox especially the manuals, give it a bit of throttle and make sure theres no movement (or close to none) in the gear lever.
MK1 had Turbo issues, seals were wearing quickly. Dare say most will have been replaced, but make sure at operating temp that there is no blue smoke AT ALL.
MK2 Had a recall for the dashboard, it had electrical issues, gauges failing etc. A few were even known to catch fire. If the car has FSH and receipts, check them for all of the above. Remember it sits on an A3 floorpan, so things dont quite fit the way they should. Pedals are quite "Porsche" like, with them being more on the passenger side than the drivers. Theres also a recess that the pedals go back into, which used to do my head in when throttling it as you had to use your tiptoes to get the pedal fully down.
Also, if the budget will let you then buy a 225 Quattro Sport. Rear seats are replaced with scaffolding, but it makes the car handle so much better with the seats removed and brace installed. There hasnt been a model or spec of Audi from 1993 up until 2008 I havent driven so if you need anymore help, drop me a line.