Harold, I'm not sure how the food industry is structured in minnesnowta but in Sydney you have supermarkets (obviously), fruit & veg shops, butchers, fish mongers etc. Then you have "wholesalers" (a lose term for suppliers who don't have a retail presence)...if you can locate "wholesalers" (I'm sure you would have them) these are your friend, they're often very keen to please because they don't have the passing trade walking past their door
Supermarket bought fruit & veg lasts between 12-24hrs in my experience. Wholesale markets about 2 weeks at 50% the cost
Supermarket bought meat is full of who knows what & unless immediately frozen lasts 24-48hrs. Wholesale you can (in Sydney anyway) order the grade, cut, weight etc at 50-60% the cost
Supermarket bought fish...don't know, never been brave enough! Fish mongers is ocean fresh (I should ad, Sydney has good seafood) & premium quality at 50-70% the cost
The old pyramid is a good guide but I think most nutritionists are recommending less grain based foods these days. But the maxim "everything in moderation" is king...this accommodates the pointy end of the pyramid
Ditch processed foods in favour of whole foods. The more times food has been handled generally the worse it is for you...white sugar for example is highly refined, if you need to consume sugar it should be raw sugar...don't buy crushed garlic in a jar buy a head and crush cloves...buy rolled oats not "minute oats" - that's the idea. Most restaurants will include "healthy" options on their menu, they are usually heavily seasoned & fat laden to give them taste & appearance - eat in! much cheaper & better for you, generally speaking
Good fats...avacado, oily fish, olives etc. Bad fats...butter, palm oil, hard cheese etc. Salt is a killer, tasty but a killer...use pepper (or fresh chillies) instead
We often buy in bulk & pre-prepare meals which are then stored frozen until required. Some tinned foods are excellent also, many are available in organic varieties...for example you can buy a tin of chick peas, ad a dash of tahini, fresh lemon juice, garlic & splash of olive oil & smash it in the blender/processor & you've got the best homous you've ever eaten...perfect as a butter substitute or on toast for breakfast
On & on it goes but that's some of the ideas we use at home to eat well & economically