Looks like your girls are 10 and 13 according to your signature. Going by that, I'd do a calendar with a note of "a year of Disney fun" to begin on the date they find Mickey on the calendar--perhaps one of those page-a-day ones...
It's not too late for Mickey ears--Claire's, the store at the mall where pre-teens catch glitter-herpes--usually has a few Minnie headbands with ears. Last I looked, they had some floral ones that were pretty cute.
Hot Topic could be another place to look for something cute; it looks kind of dark and scary to walk into, but I promise, they have a ton of great Disney stuff!
