Combine sugar and cocoa in a medium saucepan. Whisk together to break up any clumps. Stir in the water and salt and bring to a boil over medium heat, stirring frequently. Once it boils reduce heat to low, and simmer until thickened. Remove from heat and let stand 5 minutes. Mix in the vanilla. Store in the fridge.
Voila! Home made chocolate syrup! These are all ingredients I always have on hand, so it is definitely cheaper for us to make our own, then to buy it. I do think it is more chocolater than Hersheys as well.