Help with pricing

A while back we had a discussion on drinks and lemonades etc.  I finally have my recipes down and costed.  I will be making my sodas from scratch and Ill offer a couple teas as part of my concept. My cost actually isnt as bad as I thought it would be and I actually am paying just a few pennies more per serving than buying cans.  The cost is really in the cups lids and straws. 
 
So anywho as we were discussing before, I think all the labor and fresh ingredients demans a higher price than the 1.50 can of soda that other trucks are selling but I cant justify in my head like i believe chef buba was saying charging the 6 bucks that the lemonade stand charges for fresh made lemonade.  What do you think is a fair price where I can still move a lot of drinks with decent profit.  Just curious as to your thoughts I have a price in mind but everyone is telling me its too low. 
 
Also thoughts on Drink size, i was thinking 20 oz drinks, clear cups so you can see the fresh fruit garnishes