One thing to consider, please... Almost all the balloons at WDW are latex-free (there are A LOT of people who are allergic to latex, up to the level that it can kill them... speaking as one of those sufferers). The only ones that are not latex free are the ones they use for balloon animals and also the ones that are the Mickey Mouse Ears, but are "covered" in a clear plastic non-latex "outer" balloon.
Since the buses are so very crowded usually, please consider possibly bringing the Mylar balloons that are latex free, for the safety of those who are riding with you?
Enjoy the Magic, & help everyone else to too, please!