Just some backgroud for those who missed this thread:
http://www.2addicts.com/forums/showthread.php?t=1150752
I think the $51k-52k mark is likely to be where the M2 ends up. If not then the M3 enters the discussion quickly, especially if you are leasing the car. The 3 series residuals are usually more robust than the 1/2 series.