Powerade would count as a part of the dining plan as a snack like soda pop.
http://www.wdwinfo.com/wdwinfo/dining/diningdetail.cfm?Restaurant.ID=271
This menu has it at $2.35 a bottle.
Not sure if you are willing to pay for shipping but surely you could get it delivered to your room from a grocer or from home for cheaper.
I doubt it really matters but here is the info on the three products.
Powerade
water, high fructose corn syrup, maltodextrin (glucose polymers), citric acid, salt, natural flavors, potassium citrate, potassium phosphate, niacinamide, yellow 5, pyridoxine hydrochloride, blue 1, cyanocobalamin
Nutrition Facts: [Edit]
serving size 8 fl oz; servings per container 4; calories 70; fat 0g; sodium 55mg; potassium 30mg; total carbs 19g; sugars 15g; protein 0g; vitamin b6 10%; vitamin b12 10%; niacin 10%
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Gatorade
water, sucrose syrup, glucose-fructose syrup, citric acid, natural and artificial flavors, salt, sodium citrate, monopotassium phosphate, ester gum, sucrose acetate isobutyrate, red 40, blue 1
Nutrition Facts: [Edit]
serving size: 8 fl oz; calories 50; total fat 0g; sodium 110mg; potassium 30mg; total carbs 14g; sugars 15g
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Pedialyte
Fruit Flavor Liquid: (Pareve, (U)) Water, dextrose; Less than 2% of: fructose, citric acid, natural and artificial fruit flavors, potassium citrate, sodium chloride, sodium citrate, sucralose, acesulfame potassium and Yellow 6.
Grape Flavor Liquid: (Pareve, (U)) Water, dextrose; Less than 2% of: fructose, citric acid, potassium citrate, sodium chloride, artificial grape flavor, sodium citrate, sucralose, acesulfame potassium, Red 40 and Blue 1.
Bubble Gum Flavor Liquid: (Pareve, (U)) Water, dextrose; Less than 2% of: fructose, citric acid, potassium citrate, sodium chloride, sodium citrate, artificial bubble gum flavor, sucralose, acesulfame potassium and Red 40.
Per 8 fl oz
Sodium (mEq)...10.6
Potassium (mEq)...4.7
Chloride (mEq)...8.3
Dextrose (g)...4.7
Fructose (g)...1.2
Energy (Cal)...24