According to RowM:
Elope, the company known for carrying various wizard hats along with all the Warner Brothers licensed costume shop items is bringing out three new Death Eater masks. We're told there are 7 distinct masks in the film. While there are no immediate plans to produce the other four, we have pretty good guesses as to who at least two of these may be. Look for them at retail along with all the OotP merchandise this June 2007.
Thanks to RowM.