I just purchased a very similar car today. I was able to negotiate the price way down because I really didn't want the oyster colored seats (I feel like they will get really dirty), but then they dropped the price to the point where I couldn't turn it down.
I got a Le Mans Blue 2011 e90, 335 xdrive with M-Sport, Cold Weather, Premium and Convenience packages. It has Navigation, ipod hookup, Harmon Kardon sound, parking sensors and it's a manual transmission. Here's the listing if they haven't pulled it yet: http://bit.ly/uoJqHq
The list price was 45,777 with the BMW loyalty program (which I didn't qualify for... my first BMW). I negotiated it down to 41,500 yesterday, but logistically couldn't pull the trigger because I live in San Francisco, and don't have a garage to park it in... and there was no way I was going to park it on the street even for one night. So this morning, I secured a garage close to my apartment, went back... and got it for 42,500 (the finance guy refused to give me the previous offer because I walked out).
I think you have some room to move, you just need to figure out what it is about the car that makes it not the "perfect" car for you... and be prepared to walk away if you're not happy with the price. But let's be honest... the M-Sport with xdrive is pretty rare... so also keep that in mind. I had the luxury of not having any urgency with my purchase, I probably could have waited another 4 or 5 months so walking out wasn't too hard.