The main thing comes down tho proteins and the proper combination of amino acids...
It takes anywhere from 8 to 16 pounds of them in a vegetable form to create 1 pound of meat...
In other words, meat ain't cheap to produce, however, if ya' like it there are meat proteins which tend to be cheap, like turkey wings and legs... People don't eat them because they don't like them but they are cheap and if fixed properly are tasty, as well...
There is a reason why Mexican restaurants are relatively inexpensive... It's because the serve relatively inexpensive ingredients... But when you mix the amino acids in bean with those found in rice you have a complete protein... You really don't need meat or a lot of meat to maintain good nutrition in the protein department...
Now, if you have a veggie garden, like we do and Michelle does, then if yer looking to eat cheap??? Beans + rice + green veggies and you'll have the bases covered... That's a cheap as it gets but it will keep ya' healthy... Throw in some fruit, too, but whatever is cheap...