Just mix 2 measures of turbinado sugar to 1 of water in a saucepan, heat and stir until the sugar has fully dissolved, let cool completely, bottle and refrigerate. You can also use regular brown sugar, although turbinado is not that hard to find. I would highly recommend making your own syrup in general, it's much cheaper than buying it, and you can customize it as you see fit, or make different batches for different use cases.