I calculate the cost of EVERYTHING.
When I worked it was easier, as I sat next to a calculator all day long. Deanna would call to discuss something (financial or not) and more often than not she could hear me tapping away.
"Um, did you know those individual applesauce containers cost you 34% more than a jar"
One place I don't add up costs is in the garden. Granted, I don't spend like a madwoman but if I budget a certain amount for plants, know I'm gonna spend it.
Today at the garden store I bought a bunch of vegetables. The 6 packs were more than they have ever been. $2.99 a six pack. Individual plants were $1.49. Hmmm..... I did the math-$1.49 each or $0.50 each. In some cases I didn't care and bought the single plants, in others, I economized and bought the 6 pack (though I remember what 6 zucchini did last year!) I may try and plant some zucchini at my parents and in-laws.
A six pack of broccoli means $.50 a head for broccoli (organic the way I grow it) vs $2.50 in the grocery store (non-organic) plus the little side shoots that can be sauteed or used in a salad. At least I like to look at it that way. I'm not adding up the soil I just purchased or the water that I use watering or the bricks I plan on buying to edge the beds. Some things I just don't want to look too closely at. I know it's fuzzy math as they say, but I don't even care. I don't garden to save money (though I am CERTAIN I do) Just don't ask me how I know, because truthfully I don't.
This year I've planted (or purchased today to plant) the following so far:
Sugar Snap Peas
New to me-Kohlrabi and Colorful Swiss Chard
Some kind of surprise squash
3 kinds of Tomatoes
Scarlet Runner Beans