I made this costume last year for a university project.
I sculpted the mask over a plastic head and cast it in silicone, the horns are made of fibreglass and mounted on a fibreglass skull cap.
The tunic is linen, for the pattern I just took a long sleeve T-shirt belonging to the model, placed it on the fabric and drew round it with a seam allowance and lots more length at the bottom.
The pauldrons and belt are cut from a piece of very heavy weight leather, then dyed and stitched together, the stone in the belt is plastic and sprayed with car paint and the buckles I bought from a leather supplier (I think they are designed for use in saddlery).
The cloak is just a piece of wool fabric, pinned at the front (I meant to make some proper fastening but ran out of time)
The nose ring is just a cheap earring I found in claire's accessories and left it at the bottom of my tool box for a month so it got all dirty and worn looking.
I think the whole thing cost me about £350 (silicone and leather are pretty expensive!) and I made it over around 12 weeks
There's a bit more info about it on my blog :)