Yup, head to rs246 for buying guide. There are a few well documented issues to look out for (DRC leaks, aux radiators damaged, oil cooler pipes corroded, vacuum system issues) but they're so well known 99% of cars have had them checked and sorted. Service costs are in-line with what my S3 was, but consumables are generally more expensive (full set of brakes and pads is ~£2000 iirc).
Make sure you drive a couple to get a feel for what they should be like, and then figure out what options you're set on getting (buckets, SS+ suspension, nav, fbsw, sunroof etc). Forums are usually good places to find a car for sale too, there are a couple of nice ones for sale on rs246 at the moment too.
