I kinda find it hard to believe, given as much money and effort as they spent on other props, that the hero mithril shirt was machine made. Could be wrong on that though.
Also my understanding of why Elijah wore only the collar with a little mesh wasn't so much due to the value of the shirt, but because a real shirt like that, regardless of the material, would be pretty heavy, and not the light, airy, tshirt weight piece of clothing we're led to believe it is.