Why would a PS3 box be sealed? I suppose I could be wrong in interpreting that as meaning shrink-wrapped. PS3, Wii, and Xbox 360 boxes are not shrink-wrapped.
If they meant that tiny little circular sticker that holds the flap closed, then it's not hard to pull it up, replace the contents, and stick it back down.
Also, someone else did this earlier this year with an Xbox 360. Except it wasn't a phone book, it was some kind of medical book.