Scrapbook/photo album is good - especially with a 40% or 50% off coupon at Michaels.
How about Disney Dollars for the trip?
Or, if you know the sizes you could make T-shirts for everyone for the trip. Or just for her since it is her present.
A large memory card, if she has a digital camera. Can find some deals off and on. If no digital, how about film, prepaid processing, disposable cameras.
Or, collection of any kind of Disney items (pens, pads, cups,etc.) to set her mood before the trip..
Items from the fun at the dollar store thread: $1 pop-up laundry hamper, $1 shower curtain to hang (with the 3M sticky hooks that won't damage the wall) in the sink area of room so can have a private dressing area, I$1 over-the-door shoe holder to hang on our bathroom door to hold toiletries, window clings of Disney or Easter to make room look festive, pack of toothbrushes (5 for $1) with little caps to put over the tops for travel, other travel type items, glow necklaces, cheap rain ponchos,
A box of snacks to take with her?