I just purchased a 13" MBP from microcenter this past week.Trying to recall...just bought a MBP 13 a few weeks ago from Best Buy.
I don't recall any shrink-wrapping...Just the seal...
Inside the brown box, the MBP box was inside a bag. The box was sealed, and inside the laptop was encased in that shrink-wrapping and had a seal on it, that had to be broken to free the laptop from the shrink wrapping.
the cords were all nicely wound and placed in the box as well.
For me there was no evidence for my new laptop that it was touched, and for the OP he should have seen this if the ebay seller advertised as new in box.
As I posted, ebay does take the side of the buyer even if the seller states no returns. If the product is not new in the box and not functioning, I highly recommend filing a grievance with ebay/paypal. They'll freeze the funds while they perform their investigation.