I had an extra pair of front O2 sensors from my B7 S4. These were lengthened for the JHM headers (mistakenly lengthened the fronts and rears), but will work fine on a car with any downpipe configuration. They have probably 60k on them, but were reading fine when removed.
New universal O2 sensors are ~$60 each, New Front O2 sensors are $100+ each.
The Pair shipped for ~$50
In for the pics:
http://i278.photobucket.com/albums/kk89/mbgt72/For%20Sale%20Items/null_zpsf8feb951.jpg
http://i278.photobucket.com/albums/kk89/mbgt72/For%20Sale%20Items/null_zpse7613a84.jpg
http://i278.photobucket.com/albums/kk89/mbgt72/For%20Sale%20Items/null_zps0d3dc87b.jpg
http://i278.photobucket.com/albums/kk89/mbgt72/For%20Sale%20Items/null_zpsef5a8981.jpg
