Well, I was looking for a skin that costs $10 - $20, and the replacement boards are around the same price. So seeing how a skin would keep us from having to purchase multiple keyboards, it actually would be cost effective.
You should note that keyboard skins are custom fit, so anything you buy will have to be matched to the exact model of keyboard you want to protect (DELL L100 keyboard in your case). Companies like
Hooleon.COM,
FenTek-Ind.COM and
CompuCover.COM definitely sell custom-fit keyboard skins, but whether they have the one that will fit the DELL L100 keyboard is a separate issue. You will have to contact the companies directly and ask about their product availability. They will probably ask you to provide them with your keyboard brand and model number and/or pictures of your keyboard so that they can have a look through their inventory to see if they already have the keyboard skin in stock.
If they do not have the right keyboard skin for you, they might still be able to produce it, provided you are willing to order a certain minimum quantity from them. Hopefully, you will have enough keyboards lying around in your office to make this worthwhile if you decide to go down this route.
Alternatively, it is also possible to buy disposable keyboard skins that are not custom-fit to any keyboard, like
this kind. You can still type with this kind of keyboard skin covering the keyboard, but I do not imagine that it would do wonders for your typing accuracy or pleasure. Like the description says, it is a bit like giving your keyboard a shower cap to wear. If you must have a keyboard skin, then the custom-fit keyboard skins are definitely the way to go.