I know you do't want to buy stuff, but i would at least buy one pot and one pan (you could even get away with disposable that could be used more than once but i've found that it's usually less expensive to buy one medium quality pan than stock up on disposable). I would also buy one good knife (like a thin paring knife - you could use it for peeling and cutting) and a cutting board. I don't know where you are living, but try a dollar-store type of place.
buy fresh veg (tomato, cucumber, lettuce, celery, squash, onion, potato etc), fresh herbs, fresh chicken parts/fish/tofu, lemon. eggs.
for temp living i would buy 1-2 bottles of marinade also
you can make a lot of meals in the oven - put the veg on the bottom of the pan, put chicken/fish on top, sprimkle with oil and lemon, salt, pepper, fresh herbs and roast. or pour over ready marinade
I make a batch of chicken breast in the oven once a week and freeze them - marinade thm in your own marinade or store bought. i just mix oil, lemon, garlic, herbs and a little sugar or honey (I don't add salt because the kosher chicken is already salted) and let the chicken sit for about 24 hours in the fridge. then i roast them in the oven for about 30 minutes, let them stand for about 20 minutes, slice and either eat or put in the freezer. then defrost and eat with salad or starch.
you can also make rice in the oven - i mix one cup brown rice with two cups boiling water, a small amount of oil, a pinch of salt, cover pan tigghtly with tin foil and bake for about one hour. i like to add chopped veg - onion, mushroom, celery.