I’m a single guy living with a few roommates. I am a very competent cook, have broad tastes, and enjoy food. However, whenever I go to the grocery store, I find I just buy the same staples and eat them, week after week. I think I need suggestions of good things to eat/make for which I can buy ingredients up to 10 days in advance, or prepare days in advance and keep in the fridge/freezer.
I’m looking to diversify my diet (cheaply!) a little, and I need suggestions.
Stir-fry.
Soup.
Chili.
Pot roast, especially if you have a crock pot.
Roasted veggies with pasta.
It would help to know what you consider staples. For me, boneless skinless chicken breasts are a staple (I buy them in bulk when they’re on sale and freeze one or two per ziploc bag) – for others, they might not be.
In addition to “staples,” I usually buy bananas and a half pound or pound of fresh mushrooms when I shop, plus other fruits or veggies in season. (Fruits for desserts and snacking, veggies for pasta sauce or quiche or salads.) This does mean that I’m eating fresh produce about half the time – but since I also consider frozen peas a staple, I’m not necessarily green-free the rest of the time.
Most red pasta sauces freeze perfectly fine, and you can thaw them in the microwave or in a pan on the stove with a little extra water. I live alone and I usually make bolognese sauce in batches of 8 or more portions. Just freeze in in portion baggies.
Couscous is really quick to make. I like it with some dried fruits & nuts which will keep for months. You can also use some other fruits/veggies that stay good for a couple of days.
Sliced bacon will keep for a couple of weeks (especially if you keep it in the air tight packaging). So will cheese, eggs, garlic, butter. Spaghetti carbonara is one of my favorite foods when I’m too lazy to go shopping.
It’s always useful to have some yoghurt, eggs, long-lasting cream, a few hard-ish cheeses, canned tomatoes, milk, honey, flour and nuts.
Vegetables vary, but there are a few that will last 10 days in the fridge:
Chicory (great in a salad with honey and blue cheese, or in a casserole with white sauce)
Mangetouts seem to last about a week in my fridge, but lots of beans can be frozen, and then they’ll keep more or less forever. You can prepare them (cutting) before freezing so you can just plonk them out of the freezer into the pan.
Big winter carrots should last at least a week and can be used in anything from salads to stews and pasta sauce. AFAIK carrots can also be frozen (you’ll probably want small chunks for that) but I wouldn’t use any frozen veggies for salads.
Leeks will keep well in the fridge.
All in all I usually buy a lot of stuff for a week or so, and then get some fresh fruit / vegetables whenever I need it.
Also, you can buy frozen meat & fish for cheaper than “fresh” (usually, pre-thawed) meat in the supermarket and store them in your freezer. Just remember that thawing large cuts can take a lot of time (in the fridge or under streaming, cold water). Thin (fish) fillets or raw prawns can be thawed quickly in cold water.
Cheap and simple recipe: make white sauce, add some chopped salmon fillet or (pealed) prawns and frozen peas and cook till done. Season and pour over pasta. Or leave out the fish and use some more frozen veggies.
Coconut cream curries are also simple and can be made with pretty much just some frozen or dried ingredients and some onion & garlic. Example: chop up some lemon grass (another thing that you can freeze), a small onion, some garlic and some dried pepper flakes or sambal. Heat up oil, add ingredients. Stir for a minute, add coconut cream. Now add some meat, fish and/or beans/chickpeas. Cook till done. Other interesting spices to use: cumin, curry leaves (soak dried leaves before use, or use fresh), cardamom. You can also use canned tomatoes instead of coconut.
Also, I recommend this guy who has a multitude of videos on cooking techniques (NOT recipes). Very informative if you plan on experimenting more.
My shopping (and/or what I have ‘in stock’) usually includes:
Pasta
Rice
Lunch meats
Lettuce
Onions
Garlic
Broccoli
Cheddar
Pasta sauce
Carrots
Yogurt (individually sized)
Milk
Cereal
What sort-of inspired this thread was that I went to a friend’s for dinner on Thursday night. We had ravioli (frozen) and she made a tomato/garlic/onion/basil sauce that was delicious and took about no time at all; just chopping the veggies. I just never think of things like that, and certainly not well enough ahead of time so that I have the ingredients before I decide I want to make something. Usually I’ll have the idea, and then have to make a trip to the store just for one meal, which often means I’ll skip making it in the first place.
See, if you’d have bought a whole bunch of canned tomatoes & a live pot of basil (which will keep growing if you treat it well) instead of pasta sauce, you could have made it yourself 
I hardly ever buy “complete” sauces or anything like that (well, except for the occasional frozen pizza). The basic ingredients aren’t usually that much more difficult to prepare, last at least as long, and you can vary the taste to your own liking. You can use canned tomatoes for pretty much any style of cooking, from Indian to Italian - all you need is some dried herbs and spices (except for basil, that has to be fresh, though you can substitute dried oregano in emergencies).
As for the individual portions of yoghurt, I assume they’re flavored? That means you can’t use them for sauces, or dressings, or casseroles either.
I consider laksa a staple. The noodles keep in the fridge for a month, and I buy canned sprouts and coconut milk. I make my soup from a jar of sambal olek* (also keeps for months in the fridge), teaspoon of ginger (from a jar), teaspoon of garlic (from a jar), and add in chicken (from the freezer) and prawns (from the freezer). Boiled eggs can be made at the time and the extras kept for sandwiches etc. Of course, its not the same without fresh coriander - you could consider growing a few pots of herbs in the kitchen.