I'll admit my focus at the library is usually pretty narrow. I go onto the website and search vegan and then request away. Sometimes I branch out a bit and look through the new releases and awhile back I found Homemade Soda by Andrew Schloss on that list (I put the Amazon page link there since it has the look inside feature, you can even get the recipes for some if you sign in). Strangely, I have never thought to make my own sodas but the idea was intriguing. It has 200 recipes for sodas of all kinds and then some recipes that use the sodas you've made as ingredients. Most of the sodas are naturally vegan (some have milk or honey but I'm sure you could sub soy/almond milk and agave as well) but the recipes are not. The book is quirky and informative, too telling you the history of soda and all about the methods and ingredients as well. There are actually three different methods to carbonate your sodas, one being just add seltzer/soda water to a syrup which is super easy and affordable so you don't have to buy a siphon. I definitely want to try out the cola in the book but it requires some ingredients I will have to keep hunting for like gum arabic and dried bitter orange peel. It also strangely uses Kitchen Bouquet which is something I have used in the past as a gravy browner. Turns out it's basically caramel colour which I have seen on the ingredient list on some sodas.
For my first homemade soda I decided to try something simple and fruity, Strawberry Pineapple Soda. The best part of the recipe is that it only takes a few minutes to make and there is four ingredients. You make a puree of fresh strawberries, pineapple juice and the smallest amount of sugar, strain and add the seltzer water. It is so fresh and tasty without the cloying sweetness you usually get with sodas. No artificial flavours or colours either which is another added bonus to me! I will definitely be picking this book up sometime soon since the library will want their copy back but I have so many more I want to try...like Cream Soda, Rooty Tooty Root Beer, Coconut Milk Fizz, Ginger Pineapple Coconut-Cream Float and Original Orange Crush.