Halloween Time?

As most of my money this year will be tied up in several landmark family & friends' birthdays, a hen party and 2 weddings (on top of the non-landmark birthdays, anniversary celebrations and Christmas), I decided to start buying my Halloween costume one bit each month, depending on how much money from that months pay I had left. So far I have a pair of knee high socks and this backpack. Can you tell what it is yet?