I think a lot of people (even because of simplicity rather than budget) do the frozen precooked chicken breasts, carbs (rice or noodles), and frozen vegetables, home made dried beans sometimes thing, cook several meals worth every couple days and supplement protein with whey when you cant stand eating anymore plain-ish chicken thing. My buddy eats ramen chicken and microwave peas and carrots for almost every meal I think. Most of the dudes following a strict diet I know have an entire freezer full of those things. I would drop out of that lifestyle in about 2 weeks.

If you care about.... flavor... and like to cook, Thing I've been doing for the past few months is I just go to the store every night on the way home from work, hit up whatever fresh meat and vegetable (or two) that is advertised on sale that night and blacken the meat in the cast iron pan with some seasoning (seasoning that will last you forever and tastes awesome is pappys choice reduced salt, comes in a huge container, and a little coffee because it blackens to a delicious char... if you want to get fancy smoked paprika or hickory powder will kick it up a notch but that's extraneous) then when its ready I stash the meat under something to keep it warm and I hit the pan with a couple tablespoons of cheap wine (or water) and scrape up the burnt stuff (called deglazing) toss it in a wok with a tsp of oil, garlic, and soysauce and stirfry the veggies in that burnt char oil soy sauce goo and top it off with a little pepper.

I've been doing this for ages for dinner and after I eat i do a second portion for the next days lunch and then clean up. I only really take carbs with breakfast (later in the day carbs seem to make me feel like garbage) where i usually eat a lot of whatever seasonal fruit is cheap or greek yogurt and sometimes I do DIY or official soylent (that's a whole other thing a lot of people scoff at but I like making meal shakes out of stuff). It's probably not the best diet plan out there but its really easy to track calories since its mostly whole foods and seasoning, and it never gets boring or tastes bad. You can really fill up on the veggies esp if something like fresh green beans are on sale. I eat a bit high on the fat and a bit low on the carbs on this diet, but I find I feel the best on that ratio.

Granted all that dinner / lucnh stuff requires some start up cost of a cast iron and a wok and the spices... but you can find a usable cast iron at a pawn/thrift store and a steel wok at an asian market either for 10 to 15 each if you call/look around. You also need a bottle of oil that tolerates high temps like rice bran, peanut oil, etc because wok and blackening will burn (in a bad way) some oils like olive and butter. I'm pretty happy with that... It's not the cheapest ever but I mean its still a lot cheaper than buying fast food... blackening meat tastes awesome and I dont get bored of it since I rotate meats like i do premade chicken patty frozen veggies... wok'd veggies taste good no matter what you put in them because woks do something to veggies that no other pan can do. The only bad thing the seasoning adds is salt which I'm not worried about because I'm not on the 6 pack mission or anything.

Once you get into a groove you manage to make it cheaper and quicker until you know what stores to hit on what days for the meat deals and you make the food in like 15 minutes tops. Takes a while to get into the groove though. sometimes I go to costco on the weekends and treat myself to their lamb chops or fish since they have better meat, but that's if I have extra money that week.