Go for votex kit.
http://cgi.ebay.co.uk/New-Audi-Votex-Audi-A3-Sportback-06-09-Bodykit_W0QQitemZ250379104999QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item250379104999&_trksid=p3286.c0.m14&_trkparms=72%3A1683|66%3A2|65%3A12|39%3A1|240%3A1318
I am looking for one for my car, but this is one for a sportback 06>
http://cgi.ebay.co.uk/New-Genuine-Audi-Votex-Audi-A3-04-09-Sideskirt-Kit_W0QQitemZ250379091792QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item250379091792&_trksid=p3286.c0.m14&_trkparms=72%3A1683|66%3A2|65%3A12|39%3A1|240%3A1318
Just the side skirts