I take a $1.00 lean pocket (I stock up when they're on sale) and it's much cheaper than the $4 I'd pay for lunch in the cafeteria. I take a piece of fruit for midmorning snack and two pieces of bread for afternoon snack (because it's easy. If I knew another easy snack food that wasn't fruit or veggies and that filled me up and wasn't terrible for me, I'd eat that too. Some days I pack carrot sticks and hummis.)

It's really no extra time. I've got an insulated bag which a freezer pack in the bottom. (It's easier than wrangling for space in the fridge.) Somedays I also stick something to drink in there because that is way cheaper than buying soda out of the vending machines.

On days when I use my crockpot, I bring leftovers.

Oh, and chili! Every so often I make a pot of chili that makes 8 servings. I spend about an hour making it. (Not an active hour as after the initial can opening is doen, there's not much to be done but stirring once in a while.) I seperate it out into servings right then and there and then pull one out for lunch.

(Then go up to that last paragraph and replace chili with lasagna. Except leave out the part about the stirring.)

Oooh, and since it's summer, I almost forgot!
1 can of soup + 1 spoon + 1 microwaveable bowl = lunch heaven in the winter.
Very easy. Very economical if you wait for the $1/can soup sales.