Ok, now, I'm skint a good portion of the time, so, if I want something, I have to be sensible. As do most of us. I have certain things that I keep as 'staples' in my cupboards, that can go with anything, and make up anything in a quick meal.
Tinned Tomatoes: Chopped or whole (the whole ones can be chopped up. Sometimes, it's a few pence cheaper to buy the whole ones. It depends on the shop). I don't get anything fancy...just the shop's own brand (Sainsbury Basics, Asda Smart Price, Tesco Value). I usually have at least one, if not two, tins on hand at all times.
Tinned or Frozen Sweetcorn: I personally prefer frozen, but tinned works just as well. Again, shop's own brand. Cheap and cheerful, I think I tend to pay around 22p for a good sized tin.
Onions: I have a preference for using red onions, but will use yellow, if that's what's on hand. I know that our local Coop has a bag of yellow onions at a cheap and cheerful 50p, and there's maybe 7 or 8 onions in there.
I use a lot of herbs and spices, and, unless I'm following a specific recipe, I have a tendency to estimate, and do a lot of 'that looks like a good amount'. So, since I use a lot, I prefer to buy all of my dried herbs from the market in the city centre. I know I've been able to obtain them in both Grimsby and Lincoln, at the health and whole foods stalls. They also carry some spices, but, for those, I prefer to go to our local Chinese food shop. They tend to come in a reasonable sized bag for dirt cheap. Doing this saves you quite a bit from what you would spend at your major shops...where you're paying extortionate prices for a tiny glass jar. Buying from the Chinese shop, I have some spices that are the most amazing quality...mmmm....cinnamon....
For storage, since I don't like the tiny jars, I tend to wash and recycle other jars, and label them. Mayonaisse jars, jam jars, coffee jars...these are all used in our house. Eventually, though, I have my heart set on some sealing jars from Lakeland.
I am a huge proponant of buying local. Using your local butchers ensures that you get a lot better quality. The ones I know do some really good deals...i.e. 3 for £5, 2 for £5, etc. I tend to pick up two or three of the deals, and freeze for later use. Minced beef and chicken pieces are a common thing, that are nice to keep on hand as staples, because you can do anything with them. If you decide what you're making at the last minute, you can always defrost in the microwave.
Most butchers also carry eggs. If they don't, your local market is likely to. We always use Free Range eggs, because, then you know they've not been fed wheat, or loads of chemicals. I'm not massively on the organic kick, but I'm very anti GM, and, if I can afford free range, I will get it.
For those of you that are wheat or gluten free, as we are, if you are really fancying sausages, check with your local butchers. I know of one here in Lincoln that carries lovely Lincolnshire gluten free sausages every day (Pepperdine's, on Sincil Bank). Some butchers, if they don't carry them on a regular basis, can sometimes order them in for you.
As often as you can, buy your fruit and veg from your local market or greengrocers. You'll get a lot better quality, and, normally, a lot better value.
We do keep flour on hand, at all times. But, as we are wheat free, we are rather limited. We generally keep in Wheat and Gluten Free Plain, Self Raising, and Strong White Bread flours in, all made by Dove's Farm. These are available at most of the major supermarkets, in their Free From sections. If they don't have a special section, check with the rest of the flour...they might have it on one of the higher shelves (to avoid cross contamination). There are other types of flour that can be used, i.e. Spelt, Rice, Potato, etc., but, personally, I can't be asked. It can be a bit more complex, with having to add stuff like xanthan gum, etc. The Dove's Farm, for the most part, is ready to use, and I just use it like normal. You may just need to add a little bit more liquid, if you're using a normal recipe. It's a little bit of experimentation.
Well, if I think of anything else, I'll add to other posts :)