I live in Japan and my grocery bill, excluding alcohol is about $50 per week for my wife and I. We eat a really wide variety of foods, but actually that variety means that we eat
less meat. For breakfast we usually have rice, an egg, natto (fermented soy beans) and miso soup. The soup contains a variety of different ingredients depending on our mood: potatoes, onions, mushrooms (4 or 5 different kinds), daikon (a kind of large, sweet radish), carrot, wakame seaweed, tofu (very soft, grilled or deep fried), etc, etc, etc. I often have some oatmeal in the morning if I'm feeling hungry, or we'l substitute some of the rice for other grains like barley. Once or twice a week, we'll have a small piece of fish: usually grilled, but often prepared in different ways -- dried fish, pickled fish, marianated in sake lees, in a miso sauce, etc, etc.
For lunch it's always a lunch box during the week with the ubiquitous rice. However, there will be Japanese pickles, usually a stir fry, or left over dinner. We always have some meat or fish in the lunch box, but only something like 20 grams or so -- just for flavour and texture. I try to make dashi maki tamago (a rolled omlette). There are lots of preprepared things we add as well (some of which we buy, some of which we make). Things like hash browns/tater tots, potato salad, crunchy vegetables cooking in a sweet soy sauce sauce, etc, etc. The main shape of a Japanese lunch box is 1/2 of the box is rice, 1/4 is some main dish, 1/8 is some accent, and the remaining 1/8 is either fruit or pickles. The sizes are small so it's easy to get variety over the week. On the weekends, we will occasionally go out for lunch, but usually for ramen (which only costs us $5-7 each including tax and no tip -- advantages of living in Japan).
Then for dinner we have tended to adopt a kind of tapas style of eating -- which is common in Japanese izakayas (think pub). So we make 4 or 5 small dishes and nibble on them (usually with some beer or Japanese sake). My wife will spend time in the evening to make some of these dishes ahead for the week. I usually take over the kitchen on the weekends and make European style foods (though, normally "poor" people's foods like stews, etc) We often use the left overs in the lunch boxes.
One thing is that we eat very little meat/fish from a N/A perspective. Even when we eat yaki niku (Korean style barbeque), each of us will eat a maximum of 150 grams of meat each -- and that includes some beef, some pork and either a sausage or a bit of chicken. The rest is vegetables. Sometimes we'll have a piece of fish for dinner, but it's just a small piece and also just one of the 4 or 5 dishes that we have for dinner. Meat is not a main dish, ever. It's just an accent.
We don't often have desert, but when we do it's almost always seasonal fruit. Virtually every month where we live there is a new fruit coming into season. We don't eat fruit out of season -- we only eat local fruit. This means that we really look forward to it coming out and we just to buy it. Cherries are always hard because the season is only about 2 weeks!
When I worked at the high school here, the school nurse told be that the Japanese don't really do the "food pyramid" thing. Instead they recommend that you have 14-15 different foods during the course of the day.
You can see that we don't go out to dinner much: Usually 5 or 6 times a year and it's a really special treat when we do. But it's nice because the food around here is so great that it's a pleasure to cook with it.
I think the money mustache guy has it right: avoid optimising your time for work and instead optimise it for enjoying doing things for yourself. Get your calories from inexpensive things (we're mostly getting calories from rice, veg and fat). Then you can add variety, but the key is to have a lot of variety in small portions.
Just my 2 cents, anyway. There are lots of good ways to live and I don't mean to say that other ways are worse than this. It's just that you can spend a small amount of money, get a large amount of variety and not eat a large number of calories.