Ehh... That's a tough one. A few weeks ago I saw a sealed Mac SE (opened the box, but did not rip shrinkwrap from computer) on ebay that had been sitting in some guy's closet all these years. The case was virtually flawless and it still had the yellow disk guard in the drive. In that case, I would have opened it. IMO, an unopened 128k mouse is harder to find than an unopened SE. So I would keep it sealed if I bought it.