My mirror is already centre-spotted. Bintel did that as part of the package..
They took it out of the boxes (when it came from GSO), thoroughly check it, centre-spot the mirror, collimate the scope, and then put it back in the box. I guess that's what you're paying extra for - the service and reputation.
Although I got a good deal from them and didn't pay any more than I would have from Andrews. Check the other thread in the equip forum
The forecast for saturday is "sunny with clouds", so who knows what that means.. as long as it's not blanket cloud coverign the whole sky, i'm sure I can put up with a few intermittent clouds.