I eat a lot of raw stuff...

So slice up some carrot sticks, celery, broccoli, apples, oranges...throw a banana in your bag, an avocado (great protein although can be pricey).

Get some big tubs of greek yogurt, put in a smaller container to go and add frozen berries + fruit.

I eat a lot of dried fruit and nuts, which you can find on sale at times...things like cranberries, apricots, bananas, raisins, mix it up with some almonds, sunflower seeds and rice chex..you can make your own trail mix relatively cheap.

Some cheap meals involve a lot of rice and beans for me. Cook the rice and beans the night before mix up the beans with some cumin or onions whatever you like, also buy bulk DRY beans much cheaper but must be soaked in water overnight. Throw in what you have, a green pepper, some frozen corn, whatever your fancy. pile it into a container with some salsa (or cook with fresh or canned tomatoes and add spice to taste). In the morning throw on some greek yogurt (low fat alternative to sour cream) and there you have bean rice thing going on.

Stir frys are easy and cheap. Cook rice, get a frozen pack of veggies and mix em all up add fresh veggies if you have them or can afford them. Throw on some soy or plum sauce put in containers, good to go.

I like soup, so I eat a lot of it...if you make a huge pot you can freeze half of it and divide the rest for lunches. Soup is also EASY (just takes prep but once that's done you just let it cook).

Don't forget to experiment with salads and you can also make potato salad , tastes great with cilantro and sweet potatos, or with white potatos and dill. Try a greek salad if you get bored.

Other ideas...Rice cakes and hummus, pita bread and tzatziki, homemade wraps to go (put in veggies, dressing, a little shredded cheese whatever you fancy roll it up and you're good to go. you can make wraps with rice and salsa and what not as well).

Whatever you make for a healthy dinner can then be put into containers for lunch (examples of things that end up with me the next day are vegetarian chili, rice-noodle pasta with pesto etc.)