I only like one kind of cereal, and that's how much it costs... on sale. I don't like packaged, mass-produced bread either; I buy it from a European-style bakery. Fruit, on the other hand, is easy to find both cheap and good around here.
I'm thinking out loud here, not telling other people what their food budgets should be like.
Yeah, food is something you can spend as much or as little as you want. If you clip coupons and shop sales, you can literally cut your budget in half without making many sacrifices, but that takes time and effort. If you're willing to live on cheap stuff like ramen noodle and cheap hot dogs or bologna, you can live on 10-20 bucks per week. But few people want to live like that and I don't blame them.
One of my concerns about food is how much I'll have to spend on food and drink to remain social. Honestly, I'd be fine bringing PB+J sandwiches every day, but I'm thinking that I need to network with other students for study groups and that sort of thing, and that stuff is typically done over lunch or drinks or something.