Halloween costume

My little one has changed her mind up to six times a day about what she wants to be for Halloween. Sometimes she wants to be Batman; sometimes Tinkerbell; sometimes a fireman; sometimes Nemo; sometimes Dora the Explorer. How on earth can I make or buy an outfit to suit such the fickle child??

Today, I found the SuperGirl costume at Target on sale which I promptly snatched up. After lunch, I let her try it on, and (hurray!) it's a hit!