Decorating the walls of your dorm room doesn't require expensive or fancy paintings or other artwork. When you visit a thrift shop, it's common to see outdated art for sale and typically at extremely low prices. Some of this art may be appealing; other pieces may be so appalling that you can't resist using them to decorate your room. If you love music from the 1980s, for example, it's easy to find outdated, 1980s music posters at many thrift shops.
The floor of your dorm room is likely plain and may be decorated in vinyl or a thin carpet. To add some life and comfort to the room, find a colorful, thick area rug at a thrift store. Even in a small dorm room, it's easy to find a circular or square rug to place in the center of the room. If the rug is too big and you bought it for a low price, you can also trim it to size.
Most dorm rooms are basic, with little in the way of built-in shelving. Fortunately, most thrift shops sell shelving units in a variety of shapes and sizes. Your dorm likely prohibits attaching any shelving unit to the wall, but standing units can work against any wall or even in your cupboard. If your dorm's decor is already funky, you don't need to worry about matching the shelving; any unit will suffice.
If you're not impressed with the drab curtains covering the window of your dorm room, it won't cost you much money to upgrade them to something with a little more character. Many thrift shops sell curtains, and most of these are outdated and ideal for retro-themed dorms. Make sure to check how your dorm's curtains are attached, then find a set that you can easily substitute. Remember to keep the dorm's original curtains and replace them at the end of the school year.