A transmog question I didn't know where to ask.

Hello, I wanted to ask about an item appearance that I didn't find anywhere but it seem to exist as there is a person wearing it. I didn't know where to ask and if it's the wrong place sry about that. The item is called "Boots of the Underdweller" from Ulduar 25 General Vezax. In game the item texture is red and I've seen it many times and as far as I know it is re-colored in Cataclysm, but there is actually a guy on our server wearing the blue color of the item. I searched for it and couldn't find it anywhere. So my question is where can you get such item?