I go with what my budget can take and just do the best I can rather than obsess over grass fed, free range organic stuff. As Rob has said, Aldi is your friend. I also use Lidl for organic carrots and sometimes they have organic onions too.
Originally Posted by Rysia
Offal (Liver/kidneys etc) from a butcher is great value. Sainsbugs has "pie fish" which is offcuts of various fish that one can buy at a better price. We also get their Value salmon. By going to a market later in the day there's usually veg/fruit bargains. Some purists will tell you that fruit is sugar. It is, but it's better than drinking coca cola or other fizzy stuff.
By buying fresh and cooking it yourself, you will definitely keep costs lower than buying ready made meals etc.
I also watch for offers and coupons to get best value. I buy Lidl's tinned mackerel in tomato sauce, herring in mustard sauce and kippers as they're good value, although not perfect they do for me.
I am growing some spinach in large pots to go with my eggs in a sort of omelette of a morning. There are other things that are easy to grow in confined spaces that will save money as well.
My advice is just do what you can when you can so that you stay within budget but still eat comparatively healthily.
Why use a sledge hammer to crack a nut when a steam roller is even more effective, and, is fun to drive.