Create a small and cheap list of ingredients to be able to make as many cocktails as possible.

Based on your request for a small and affordable list of ingredients to make multiple cocktails, one of the best options would be to start with the versatile and popular base liquor, vodka. You can then add some lime juice, tonic water, grenadine, and possibly some tequila añejo. This selection of ingredients would allow you to prepare a variety of cocktails such as Vodka And Tonic, Tequila Mix, and potentially more, providing a good range of flavors and options while keeping costs and inventory manageable.