Here's my 2 cents:
* shop where you live....you dont want to have extra baggage/luggage, especially w/bulky fall items, you won't be able to return/exchange anything, sales tax may be higher
* kids may not enjoy that much, especially with all the other attractions Orlando has to offer
* get school supplies now while all the great sales are coming out - get those back packs geared up and ready to go BEFORE your trip, not during it - you really want to drive around traffic-clogged Orlando looking for loose leaf paper and calculators? Instead, go to the pool and order a fruity drink with an umbrella in it, while patting yourself on the back for having already purchased your back to school items!