You should take note that it is an 06 with competition package, SMG & warranty. Sounds like a good deal. Those Competitions package 06 M3's went for 58K-60K new. The price drop is drastic but since the new e9x M3's came out so has everything. The competition package comes with a lot of upgrades not availible for the regular M3, including a more direct steering rack, CSL style BMW distributed wheels, exclusive interlagos blue color, larger rotors + cross-drilled, alcantra steering wheel, more agressive DSC setup, interior aluminum trim, and some other stuff.
I quickly found this australian article on it. Looks to be pretty old. BMW M3 Competition Package: Another Winning Combination - AutoWeb News