I picked up a two year old 2012 50i with 24K miles for about $52K before taxes.
It is loaded with the exception of the Cold Weather Pkg and still has 2/25 left on the warranty. You could get a CPO for 3K more.
Not sure about the Nav in the F15. It looks the same as my 09 335i and the E70.
If you want something with lots of room and a third row, look at the GM Lambdas - I have a Traverse and it is huge inside. Much bigger than you think. If you want a bit of luxury, look at the GMC Acadia Denali or Buick Enclave versions. They are not BMWs but are actually not bad at all.