if you have the stones, there's a pretty good argument for doing what cannonball2 is doing here
and buying the motor in pieces and doing the assembly yourself.
It loads all the hard work onto you, but removes the the random chances of getting a bum motor delivered.
But, to be honest, what I would do is look at the other stuff that comes with the motor, let's say I wanted a short intake, I'd buy a motor that says it comes with one. Or maybe one with a better looking throttle grip, or some upgrade like a chain tensioner in with it for a discount.
That, or just buy one that's on sale right now.