They probably sent it out to be done... and of course, no one ever charges the army more then what their product/services are worth....
Anyone looking to get somthing printed on tyvek would be charged a little extra for the cost of the materials, and a lot extra because of the novelty of printing on tyvek... add the "rip off the government" fees and you can imagine the cost increases...
Not having done it myself, as near as I can tell, you buy the tyvek, cut it to fit the printer (with the exception of laser jets, won't print on laser jets, due to the heat in the printing mechanism melting the tyvek) and press print. (From dupont's website... http://industrialpackaging.dupont.com/5techtips/index.html)
The biggest hassle would be cutting the tyvek, which would NOT be a hassle to a properly equipped print shop.
Hopefully this doesn't end up like the time somone claimed you couldn't shred a slice of pizza... you can by the way....