We are doing this for all of our 5 and I have been picking up small things here and there since Christmas-
I have 4 boys ages 7,10,16, & 17 and one girl age 12
Very hard for the older kids but I have managed to find quite a bit for my DD w/ Fairies just coming out- (she is not into HSM or Camprock at all)-
you could do a few Disney themed pens/markers- sunglasses (Disney or not), a ball cap, beach fishing style hat, magnets, stickers, disney dollars, a mini phone book, a journal, autograph books, pressed penny tubes (m&m tubes w/ quarters and pennies), lanyards for pins/tickets,etc, candy (always), Disney lip balm (avon or wal-mart), fanny packs w/ disney characters on them, a tote (can be the "goodie bag" to add everything to), Disney towel for the pool, think of what your kids like or will need while there and then decide of the character or movie they enjoy most and find items that coincide... I would check Target (loads in dollar section as well as Dollar Tree- (also lots of Disney stuff)-
For the magnets & stickers go to the Creative Design board- they will make you about anything you can imagine and all you have to do is print it out on magnet paper, iron on transfer paper, sticker paper, etc and you take care of the rest! I also have shirts I made for my kids through that board! They are amazing over there!