AntiTrumpAlliance

I'm not the OP, but this one is pretty simple to answer. So you need three things to survive - calories to burn for energy, protein to build and maintain muscle, and vitamins to help keep your organs running smoothly.

Beans and legumes are densely packed with protein, it's basically the second best thing next to animal meat, and they are generally inexpensive to buy. You can buy them canned or dried in bulk and it lasts basically forever either way. So that covers your protein intake.

Similarly, rice is also very cheap, plentiful, and filling. Carbs are a great source of calories that give you energy, so you want to get the best bang for your buck and get a sack of rice or millet. It also lasts forever when properly stored, so buy the gigantic bag of it at the store and save with the bulk pricing.

Most vegetables provide basically nothing in calories, but are loaded with tons of vitamins, and if you get a healthy variety of them you can cover most or all of your bases without having to rely on vitamin supplements. Plus, as long as you are not shopping for organic produce, vegetables are generally pretty cheap to buy a good amount of. Spoilage is an issue, so you can't really buy in bulk, but some keep longer than others and assuming you live near a supermarket it's not difficult to get fresh produce to cook every day.

So the answer is, if you buy in bulk you can eat beans and rice with veggies or a side salad and have an incredibly boring but nutritious and filling meal. If you have spices in your spice rack, you can go a little nuts with trying out different things to see how it affects the flavor just to get some variety in your palette, because trust me, you will get sick of beans and rice even if you are saving tons of money on food costs. Even the most frugal people I know understand that it's not a proper long term solution, it's a struggle meal that can carry you to your next paycheck if you are in a pinch.

It's mostly beans. They're about a dollar per pound dry, which is approximately 1,500 calories, so a grown man needs just $1.50 per day to supply his calorie needs while getting a decent amount of protein. Other dry bulk goods (rice, flour, etc.) are comparable in price, have less protein overall, but supply specific amino acids that beans don't provide much of. Relatively cheap vegetables (sweet potatoes, carrots, cabbage, etc.) can provide vitamins but I would still take a vitamin supplement if I were on this diet, at least because since it's vegan there is no B12. People who eat meat will have an easier time.