Acquire a mini-refrigerator. These are typically about 3 feet tall and can have a small freezer section. If you're unsure of what they look like, think hotel room mini-bar. Having a mini-frig will allow you to shop for perishables and store them for later use. You can usually find these for sale in your local classifieds, at yard sales, end of term dorm room sales or at local thrift shops. If you can't find a used one that suits your needs, try one of the mega-mart discount stores. You can usually find new ones starting under $100.
Next you'll need a way to cook your food. Check your college dorm rules on what you are allow to bring in. They typically don't allow anything with an open flame or burner (hot plates, camping stoves or broilers), but do often allow items such as a microwave. In this type of situation, a good microwave can be your best friend. Again, you can often locate a used one in the classified ads or local thrift store. Try to purchase a model that has a rotating cooking surface as this will cook your food more evenly. Don't opt for the cheapest model available, as these are usually lower wattage units and will take forever to cook even simple dishes. Your new microwave can be placed on top of your mini-fridge to conserve counter space. Since they don't put off a lot of heat, there shouldn't be any fire or overheating hazards.
Although you have probably never used one, a crock pot can be a great addition to your kitchenette. Crock pots are extremely versatile and can be purchased new for about $30. They are great for simple items such as soups and stews, but can even be used for browning meat or steaming vegetables. Most come with a recipe book for lots of new ideas which can expand your culinary boundaries beyond chicken flavored noodles.
If your dorm rules allow, you can expand your set-up with the addition of a toaster or toaster oven. Both of these items provide methods of cooking that can't be accomplished with a microwave or crock pot. They are great for quick grilled cheese sandwiches or for warming up leftover pizza. You can usually pick up a toaster oven in your local discount store starting at about $30. Again, check your dorm rules before adding a toaster oven. They have exposed cooking elements and may not be allowed.
Once you have setup your kitchenette, you're ready to get started. At this point you'll probably need some cooking utensils and containers. Consider your setup and purchase accordingly. You probably won't need any pots or pans, but some good, sturdy plastic bowls and plates will be helpful. You can purchase sets of these in your local discount store and some even come with plastic stirring spoons or spatulas. Keep in mind the size of your microwave and mini-frig so you don't purchase items that won't fit. Sandwich makers, coffee makers and electric grills also make great additions.