dude, dude, dude!
I have bought 1 cpu in my life brand new...and regret it terribly because it was the worst clocking of them all.
Buying used is the way to go, modern CPUs are nearly indestructible! I ALWAYS buy used CPUs.
Things I usually would rather buy new are stuff like motherboards and graphics cards as they are far more likely to go kaput during their lives with me.