I think I know why I and many others didn't get a Best Buy code yet. When I preordered I got the one receipt that showed only a $5 charge for the game. When I went in yesterday to pick up my copy, they took that receipt in as an "exchange" which is reflected on the new receipt, and replaced it with the actual game with the $5 credited on the new receipt. So by "returning" the original receipt it may have tricked the system into thinking the sale was cancelled and not giving me the code.
From what I hear the 1M isn't so great in the game anyway