We are buying a new (to us) home, and will replace the cheap old door with a new one. What's the safest door (and accompanying hardware) to get? We're leaning towards a steel door, and I've read we should buy a mortise for it at the same time. Does it matter if we buy an inexpensive ($99) steel door or a more expensive one, in terms of safety? Any other thoughts towards ensuring our exterior doors are as safe as they can be? Thanks!