Lumis/Umbra are a good choice for Rare Hunters, you can be distinctive
But if I recall, their Rare Hunter outfits are actually different from Manga Maliks. For one, your fabric will need to be that dark purple stuff you showed in the pictures.
Costume:
I made the Rare Hunter cloak myself, and it's not so hard. You should be able to find a pattern quite easily at a fabric store for a cloak like that. A clerk will be able to help you. Follow the directions on the pattern and you should be set.
You can get the chain from Home Depot or a hardware store like that.
And you can just paint on that eye on top of the hood.
Mask:
Hrm, you missed a good time to get masks from Halloween but you could probably find a masquerade type masq at a specialty store or costume store (like the kind they use for harlequin type dances and such), cut it in half and paint on the designs, teeth, what not. You'd need to patch the eye and make it that upside down crescent design to make the mask accurate. (You'd only be seeing with your other eye)