This store has two sections, the second you might easily miss out on.
Walking in you come into the store area, selection of costumes/wigs and sfx make-up. The usual stuff you expect a place like this to have.
Although they have plenty of accessories with which you can put together an outfit there just is not enough full costumes sets, which I suppose from a business perspective is fine because this place can charge silly prices for individual accessories.
They do keep a catalogue of outfits at the till counter from which you can take your pick and either they will try and get everything for you from the store or they can be made to order.
I am sure that within this area there is also a closed back room where an Asian man makes masks (reminded me of the key maker in matrix 2) and a ballerina outfit section (I may have just imagined this also)
As I was exploring I saw a doorway leading into another large shop area and this was mainly for renting outfits. Now this was pretty crap nearly all the outfits were vintage, or Brave heart extra outfits but for Halloween definitely not much of a selection.