One example is bread. I was baking bread the other day, and obviously the cost of the ingredients I put in the loaf are less than the cost of buying a loaf at the supermarket, but that doesn’t include the cost of putting the oven on.
Or dry beans vs canned beans; does the cost of boiling the beans actually bring the cost up to be equivalent to canned beans?
I know that everyone’s energy costs are different so it’s not possible for someone to do the calculations for you, but I’ve never bothered to do them for my own case because bills I get from the energy company just tell me how much I owe them for the month, not “you put the oven on for 30 minutes on the 17th of June and that cost you X”. It sounds like a headache to try calculate how much I pay for energy per meal. But if someone else has done that calculation for themselves I’d be interested to read it and see how it works out. My intuition is that, in general, it’s cheaper to make things yourself (e.g. bread or beans like above), but I couldn’t say that for sure without calculating, which as I said seems like it would be a pain in the ass.
I have been the home cook for 6 people for years on a tight budget so I do this a lot.
For me it really comes down to sales and effort. I really can’t beat a $.99 pound of pasta making it myself, I have tried. So i buy things like pasta, bread, tofu that I could make but the savings if any would be minimal especially after factoring in time.
Instead i use the time to make the more expensive dishes, things like pickled onions and slow roasted meats for my carnivores and compound butters and sauces and dressings. These elevate the meals and i’m able to make them far cheaper than I could buy them so the time spent ends up being worth it.
Sometimes there are sales that move all this math. My kroger just had a sale on salmon cakes, something my meat eaters love but i normally would make myself. But on sale for $2 each, i bought like 10 of them for the freezer they will be massive time savers in a pinch and will come in under what i could have prepared them for because of the sale!