I really don't understand this. The delta is $100, which is nothing for pinball. If it's local, why do you need to trust the seller. There is zero risk unless you are worried about getting robbed at gun point. Look at it and if it is isn't to your satisfication walk, if it is then cash on the glass and load. You'll know after looking at and playing how usable it is right now.
If you come across anther SS or DMD in this price range and even think enough to post a PS thread. It will be gone. They guys that get games for this money are the ones that can be there right now, cash in hand and a truck.