Yikes! E90 looks so much better, more special now also since it's the last V8 M3 sedan.
The american dealerships have to discount the hell out of this type of car just to move them off their lot. I can't imagine the depreciation on this thing. It doesn't even seem to be the car you want, since you'd rather have the sedan.
It looks like you are trying hard to justify buying something you don't really want. Don't buy a car to prove others wrong or because it it heavily discounted, buy what you really want.
My USD $0.02, but feel free to ignore :-)
2015 M3 6MT Stripper | Yas Marina Blue, Cloth, CF | Adaptive M Susp, 437M
2013 X5 xDrive50i | Carbon Black | M Sport + M Perf, 333M Wheels