If I remember right, my co-worker (he sells the Toughbooks, and other brands) said the next nearest machines are ones that cost about $10,000 apiece. In fairness to those, they are supposed to be even more ruggedized that the "fully ruggedized" Panasonics. The Panasonics are expensive compared to other units as far as features, but they are much more well built. My salesperson's laptop is similar to the Toughbook 48 (I think it is the 41 semi-rugged). His unit has seals for all the external ports. The HDD has a gummy cushion surrounding it for shock protection. When you press on the LCD, you get a lot less deformation than on other brand's LCDs.
You do have to concerned about humidity. I have worked on several laptops that when you open them up you can see corrosion on some of the circuitry and all of the metal shielding.