Stocking a bar doesn’t have to break you. If you have a few of the basics, most everyone will find something that they like.
You can start with the some different kinds of water (sparkling & flavored) and soda. A cola product and a lemon/lime product are wise choices.
Basic beer is good. Check with friends and see what they prefer and pick up some regular and light.
Red and White wine are always welcome, as is Champagne.
For mixed drinks you can pick up bourbon, gin, rum, vodka, tequila and whiskey. Don’t forget basic juices like Orange and Tomato.
Make some home made wine coolers by combining equal parts of wine, fruit juice and a fruit flavored liqueur. Experiment with combinations until you get the sweet taste of success.