I can't seem to find anywhere that would sell anything like that.
This isn't the kind of thing you buy. It's the kind of thing you
build yourself.
For the leather, contact your local SCA chapter leatherworking guild and ask to buy a roll of strapping leather. While you're at it, take some classes and they'll teach you to to work with it. Don't bother with the wax-boiling routine. You don't need it for something like this. The fur...that looks like a real dead animal pelt to me. My suggestion there would be to head to a thrift shop and look for women's fur coats you can cut up for parts. For feathers, visit your local pond. The beads you can get at any crafting store. For the metal detail on the bracers and armbands, try a fabric store and/or Michael's. The armband looks like simple loops threaded together with a leather shoelace. The metal on the bracers...I'm not sure, but those might be frog clasps. Look around and you can probably find something similar. For the straps on the boots, it's a pain to make those. I suggest you cannibalize old boots or backpack straps. Again, thrift store. The staff is a stick. Look around, you can find one. For the skull, try ebay. For the belt and bags, thrift store.
That's an excellent piece of work, and whomever made it probably spent a lot of time on it. In fact, I would guess that probably wasn't made in one piece, it was probably put together piecemeal over a couple years. If you're going to commission something like this, plan to plan pay four digits. There's probably $400+ worth of material alone in there.
Alternately, if you just want something "good enough" and that won't take 6 months to build, just buy some misc. fur and leather pieces at a thrift store, cut up an old pair of pants as a base to attach stuff to, and you can probably cobble something together over a couple weekends for under $100.
Also, you probably won't be able to use a conventional sewing machine except for cloth straps on the inside of the costume. Plan to use a mix of hot glue and hand sewing.