[TexasJack]

First, that is rather stunning that it took a year to get a response to a pretty good question!

Cheap? Umm, I'd say it depends on the knife. Chris Daigle made several push knives for guys fighting in Afghanistan and used Kydex for the sheaths. They looked very nice and were very practical for the application.

Kydex is pretty cool stuff to work with for any number of applications, including using it as an interior or support in a sheath or holster. I've used it to make the belt hook for an inside-the-waistband (IWB) holster and it was pretty easy to make exactly the shape I needed with a cheap heat gun. There are all sorts of rivets and eyelets and other accessories that can be used to customize a Kydex application. And - considering how easy it is to shape - the stuff is remarkably durable.