Definitely bring with us. We always drive, so we're able to pack extras. For my trip last weekend, with me doing the half marathon, the warmer weather conditions, and me needing to make sure I had a decent stream of snacks, water and Gatorade, I brought things with me. With a bottle of water at $2.50-$3.50 at Disney, a banana costing well over a dollar and other snacks being pricy, it made sense to bring things with me. I would have easily spent $50 on water alone had I not. I say if you have a car and can swing by a store, or bring things with you, definitely do it.