Don't buy simple syrup. It's easy to make, easy to customize, and the recipe is easy to remember.
Equal parts sugar and water. That's all you need to remember. You can double or half the recipe if you want.
Below is the basic Turbinado Syrup that I make all the time as well as some variations I've made over the years. I like Turbinado because it gives it a richer flavor and it's easier to find than Demerara sugar. If you don't have Turbinado, use plain granulated sugar. If you want a richer molasses-y flavor, use brown sugar. You want to throw in some vanilla or cinnamon or herbs, throw them in. You can't go wrong.