Here's my formula:
1 pack http://www.bodybuilding.com/store/trace/stamina.html
2 scoops http://www.bodybuilding.com/store/sv/xtend.html
1/2 teaspoon sea salt, http://www.vitamin-discounts.com/pro...lt-9oz-900036/
(optional) 1 cup pickle juice or coconut water
Add water and ice to fill a 32 oz sports jar. Also bring a 2 quart jug of water if they don't have a water fountain at courtside. Drink it during your match.
When you add up the costs, it's actually cheaper than Gatorade which relies too much on sugar. Sugar is only good for short term energy. This mix will give you plenty of long term energy and electrolytes. I added extra salt because I'm prone to cramps, and it really helps in that regard.