So there is a limited number? If not the item will get less and less rare.
Also who in those thousands has the credits to buy this mask?
I would be curious to know the results of your auction
The number is limited by the random drop rate and the number of people buying the packs. Over time they will become even more rare as the number of people buying the packs goes down. Also every item that is 'claimed' and worn is taken out of the potential pool of available masks.