New X5 5.0 vs. Used X5M? Also, question re: Monte Carlo Blue

[IGotId]

I've been debating my next car forever! I'm looking for a replacement for my e46 M3 & need a ride that will work for me (my 3rd & last child was born a couple of months ago). I'd been dead set on getting an e90 M3 0r CTS-V wagon but have finally come to accept reality...neither will take 3 carseats. My wife & I saw a Carbon Black X5M in our local dealership & to my surprise, she loved it! There's no way I can afford a new one right now but we could pickup a new 5.0 or search for a used X5M...your thoughts?

Also, does MCB command a premium over other X5M colors?

TIA!