Depends exactly on your definition of healthy... like how fatty of a meat are you willing to eat.
Leaner beef or boneless skinless chicken breasts are gonna be more expensive yet healthier than less lean beef or dark meat chicken pieces for example.
Things I make for multiple lunches are:
Pasta with meat sauce:
brown 1lb of meat while boiling half a box of pasta.
when meat is browned drain fat out, put back on stove on lowest heat possible and add a jar of pasta sauce.
when pasta is done strain the water and throw in with the meat and sauce. Makes 3 big portions or 4 medium sized portions, depending on your appetite.
Costs me about $6-7 and takes less than 30 minutes to cook, portion out, and wash the dishes.
Chili:
Brown 1 lb of beef while you put one can of tomatoe sauce, 1 can of kidney beans or chili beans (I prefer kidney beans) and 1 smaller can of tomatoes and chiles.
When meat is browned toss it in with everything else, add some salt, pepper, and hot sauce to taste. I don't cook it for an exact amount of time, depends how much time I have really but the longer you can cook the better it will taste,
its even better from a crock pot but that takes more time/planning ahead. After a little bit (can be as little as like 10 minutes) portion it out and put in fridge.
Once its cool add a handful of cheese and 6-8 saltine crackers.
I get 3 hearty portions out of this and it probably costs about $9, maybe $10 total depending on the quality of the beef I use. Takes about 45 minutes, can probably do it in 30 if I'm strapped for time.
Chicken Tacos:
! lb of chicken (I use chicken breasts or chicken tenderloins, I guess thighs would be a cheaper but less healthy alternative but i'd recommend breasts) Pan fry with seasoning (I have this fajita seasoning that is salt, pepper, garlic and onion powder, but salt and pepper by themselves works great)
Once its cooked add Buffalo or hot sauce to taste, once all the chicken is coated with it take it out and portion it out. You should get about 4 good portions for tacos.
Pack tortillas (I strongly recommend the very small tortillas) shredded cheese, and sour cream if you want it. You can also do lettuce and tomatoes but the problem with these are they take a good amount of time to shred and dice, or if you already buy shredded and diced tomatoes they're actually pretty expensive imo. So I just stick with the meat, cheese, sour cream and tortillas.
$ portions out of this, you will have many left over tortillas, sour cream, and maybe even some shredded cheese left over, perhaps for another lb of meat? I usally do 1 week of chicken tacos then 1 week of beef.
All in all this costs me about $8-9.
Beef tacos:
Same as chicken tacos but use beef instead of chicken, best/easiest way to do the meat is buy on of those cheap taco seasoning packets and follow the directions on it.
Costs about the same as chicken tacos, depending on how lean the beef you use is.
Well that's my go-to lunches right there, they're what I eat most often, hope you like em!