It is so much cheaper to cook your own food even if you take into account buying the supplies. I have a cutting board ($5), a small non stick pan ($20), a medium non stick pan ($30), and a 6"-8" diameter 4" deep pot with a lid. I have some nonstick spray, some spices, a knife or two, a spatula, flipper thing, and tongs.
My total investment has to be under $100. I've been using the same stuff for 5 years now. I assume you have a toaster, a microwave, and a coffee maker already.
You'd be surprised the difference in your day between having a bowl of cereal to start off, and having a bowl of cereal, an english muffin, and a bannana. That doesn't take any extra time to do (toast the muffin while you eat the cereal).
For lunch I make myself a sandwhich and throw in some other stuff. Sure, that takes 2 minutes.
Dinner is the only meal you actually cook. You definitely save money cooking yourself. Compare $7 to $15 for chinese, sushi, pizza, burgers etc to $3-5 per meal. If you can cook pasta (boil water, add sauce, its the same as ramen. throw some freezer meatballs in the oven at the same time and your're done), chicken (throw a little olive oil in a pan, put it on medium, flip once in a while, cut it and make sure there is no pink left, don't over cook it) and steam vegetables (boil a little water, put the lid on top, steam it to taste) you can eat 3-4 nights a week really healthy with some variety.
Then fish is just a variation on cooking chicken, you just do it quicker. Your variety comes from the spices or condiments you throw on the chicken.
Total time is around 1/2 hour per day including cleaning up and eating. Each of those meals takes under 10 minutes.