Walmart's sugar free drink mixes are half the price of Crystal Light, come in many of the same flavors, and taste just as good or even better. I've tried the Sunrise Orange (like sugar free Tang), peach, peach tea, raspberry ice, lemonade, grape, and cherry. They're all really good and dissolve better than any of the sugar free drink mixes.
I got this recipe from a Joanne Lund cookbook for an amazing sugar free lemonade.
Prepare 2 quarts of sugar free lemonade according to directions. Take 1/4 to 1/2 lemon - skin, seeds and all (or if you want to use up the whole lemon, you can add the fruit or juice from the rest of the lemon). In a blender or food processor puree the lemon with about 1 cup of the lemonade. Add the mixture back into the pitcher and mix well.
I usually double the recipe using a gallon pitcher, and sometimes use one lemonade and one other flavor (peach, cherry, raspberry ice).
The recipe said you could use an orange or lime instead. I have not tried the orange, but the lime was horrible. It is too bitter, and gets even more bitter as it sits. By the second day, I thought it was undrinkable