Truvia - Stevia Plant

Pretend I'm making a pitcher of kool-aid. How much truvia would I use and about how much would it cost?
I always buy the generic crystal lite kool aide type mix with the zero calorie sweetener already mixed in. For about $2.50 you can make three gallons of sugar free kool aide.
My health-nut english teacher recommended this to me. I, being a teenager, nodded politely, before proceeding to have ignored him completely.