There's loads of AUto/SMG's for sale on Autotrader and even Ebay.
I read the ads most days and it seems about 1/3 that catch my eye seem to turn out to be auto's. Maybe because they seem slightly cheaper than the more popular manuals
Failing that here's one thats appeared today/ Although a 2.5, dont discount them if it ticks the other boxes.
http://www.z4-forum.com/forum/viewtopic.php?f=41&t=82434