I suppose that in a pinch, you could also use Trader Joe's simple syrup; but it's so easy to make this I'm not sure why you would buy it pre-made.
Ingredients
2 c. organic granulated sugar
2 c. water
Directions
Combine water and sugar in a saucepan and cook over medium heat until the sugar has dissolved completely. Remove from heat and cool to room temperature before using.
This stays "fresh" for weeks in the refrigerator.