Suggestions for a $50 Budget
For this budget I recommend investing in three different base spirits (choose your favorites from Whiskey, Vodka, Tequila, Gin and Rum). If you aren't sure what you like yet, Google some of your favorite cocktails to see what they are made with. I also recommend one bottle of bitters. Start with Angostura or any aromatic cocktail bitters, because you can use them in a huge variety of drinks.
Here are a few recipes you can make with my choice of base spirits pictured above (Vodka, Gin & Rum) and common kitchen staples (like juice and club soda!): With Gin you can make a Tom Collins, a Gimlet or a Gin Sour. With Rum you can try a Mojito, a Hurricane and a Painkiller. With Vodka you can make a Bloody Mary, a Screwdriver or a Salty Dog. See? The possibilities are endless!