Try these as well
http://www.autotrader.co.uk/classifi...335i?logcode=p
http://www.autotrader.co.uk/classifi...335i?logcode=p
Both low mileage with iDrive and may not have the HD Nav but still will have a greater resale value than the non idrive..
As P5UML has said the iDrive is really handy to have from info about all servicing, light warnings/failures to lots of info from nearest attractions on destination and so on. Yes not essential but if you have the choice, don't think twice! 335i's are going for cheap and it's a good time to buy I think and less people tend to shop for metal in winter so good way to knock off a few ££ ..
Also try ebay / PH..