This time (end of the cycle) is the worst time to buy M3 in terms of pricing. '08s with 40-60k miles have not moved from $38-48k range in about 2 years. Good entry was 2 years ago.
Now it is something like this:
KBB lists '08 as $34-36k car which is where it realistically should be. The fact it is still ongoing model carries that $5k premium.
I am waiting until end of 2013 to pick up an '09.
2000 M5, 161k, Ronin edition
2011 Cannondale Caad 9-5, 52mph top speed