I almost always pack--buying is usually if I forget my lunch. Usually I can find something, because my school has a salad bar, except for at the very end of the year. Occasionally they have vegetarian soup. If they don't have those things, they have fruit most of the time, and I can get trail mix from the vending machines or mooch something I know is vegan from a friend, lol.
If worse comes to worst, they have french fries..