You likely already know this, but the biggest factor in the cost of a diet is how much of your food you make yourself.
Prepared foods, packaged foods, and eating out drive up the cost of your diet.
The cheapest groceries:
* "dollar store" legumes, pasta, peanut butter ( only get unsalted, unsweetened ) and frozen vegetables
* sunflower seeds are amazingly cheap. They are an extremely good source of vitamin E, zinc, selenium, and other minerals. I would bet that
sunflower seeds ( get dry roasted, unsalted in supermarkets ) are also the easiest way to get these hard to get nutrients too.
* flax seeds ( ground ) are cheap. They provide many minerals and healthy types of fiber that will help lower your blood pressure. Many minerals too.
* HMart and other Asian markets offer amazingly cheap soy products, produce, and grains. May not be organic though, though that is changing.
* seasonal produce is cheaper.
* yams, sweet potatoes, cabbage, dried legumes, rice, pasta, peanut butter, frozen vegetables are the cheapest foods all year long.
* if you have the discipline and time to shop without buying make regular rounds at Whole Foods. They often have really good sales ( and quality )
on their "365" generic brand products.
* Vegan products at Aldi and COSTCO ( even without a membership ) are all the rage for the lower prices.
There are loads of "grocery haul" vegan videos on youtube and videos of how to eat for the most minimum cost.
I watched this interesting ~7 min PBS
video about a book called
"Good And Cheap".
The book started as part of a MA in Food Studies at New York University for
Leanne Brown.
She wanted to teach people circa 2015 who were dependent on SNAP ( "food stamps" ) how to get better nutrition while staying within the limits of $4 a day per person.
She eventually compiled her recipes and tips into a book. You can buy it at the link above. Each copy you buy goes toward providing free copies to economically disadvantaged people. You can also go to the "Good And Cheap" link above and download a free PDF copy.
Most of the recipes are vegan, you can ignore the rest. It is worth the free downloads because the book is about grocery selection and cooking techniques to save money that can be applied to any diet.