I do my best to eat healthy on a fairly limited budget, and I make some sacrifices over what I'd consider optimal, but I think I do alright. We've got a 2 month old at home, and my wife was mostly incapacitated due to constant vomiting for the entire pregnancy, so I've been doing just about all of the cooking for the better part of a year. I've settled into a bit of a routine.
Breakfast - Eggs are cheap protein. Potatoes are also cheap - they're starchy, but they grow in the ground and I don't feel *that* bad about eating them. Some kind of fritata with some kind of meat for flavor - bacon, sausage, lefovers, etc for me. My wife really likes a particular asparagus/ham quiche, so I'll make a couple of those on the weekends and that's an easy heat up breakfast for both of us.
Lunch - Salad. I make a couple salads most nights from veggies I get at Costco. I dress it up with some feta, green olives, and walnuts, and top it with some chicken. Rotisserie chicken at Costco is $5 for a 3 pound cooked chicken, and I can make broth with the carcass for soup or cooking rice/quinoa in to give it some added nutrient value. Or I'll just grab some boneless/skinless thighs from the freezer, they're a couple bucks a pound.
Dinner - Some kind of meat and vegetable. Our most expensive food items are the 1/4 cow and 60 pounds of wild alaskan salmon we buy in bulk every year. I've got a smoker, so I like to make pulled pork too. $1.69 a pound, and it's delicious after all day on the smoker. I pull one shoulder to eat for dinners, and I slice another to put on sandwiches for lunch if I'm too lazy to make a salad the night before. I usually eat whatever veggie happens to be in season. Right now that's a lot of asparagus and brussells sprouts.
$2/meal is my goal, $2.75/meal is my budget. It's not what I'd consider the best diet in terms of health, but I've got price and convenience to factor in too.