A few months back some readers will remember seeing a B6 3.5S for sale in Belgium for around €35k (around CHF 42k). If I remember well, that car was the last of the line and was quite well equipped (leather, a/c, sunroof). It also was advertised as having similar mileage. I don't know what it sold for in the end, but this shows that "average" mileage cars seem to be going for around €35k. Totally unmolested original cars with low miles and A1 provenance will no doubt command significantly more as they qualify as collectable.