This officially licensed Forsaken mask costs about $40.

This officially licensed Troll mask costs about $40.

This officially licensed Tauren mask goes for $100 and up.

This officially licensed Orc mask goes for about $30.

There appears to be 2 types of officially licensed Undead prosthetics available. The one labeled as "Forsaken Prosthetic Kit" is a lower jaw. The one labeled as "Undead Prosthetic Kit" appears to be a latex sheet of scars. Either cost about $20, some websites sell them for up to $30.

Officially licensed Blood Elf ears. $15 or less. Wig not included. Notice that hair is draped over the ear to hide the seams where the prosthetic meets the skin.

Officially licensed Night Elf ears are available ($15 or less) but to play the part like these official Blizzard costume models, some mauve face and body paint will also be required. Notice that hair is draped over the ear to hide the seams where the prosthetic meets the skin.

Photo Credit: arycogre