What I used to do is to actually keep track of how much money worth of groceries are in my cart. Eggs go in the cart, put $1.69 in my smartphone. A bag of pistacios - $9.95. And then when I had everything from my list in the cart (plus maybe some potential impulse purchases) I'd add it all up. If my budget was $150 and when I added it up it was more than $150 (which was usually the case) I'd put things back on shelves until I got down to my budget. (These figures are 1) U.S. dollars, 2) don't include tax, 3) from quite a few years ago, 4) poorly remembered, and 5) for a family of 3 (plus two dogs). So don't freak out if these figures don't match up with what you think reasonable figures for you might be.)
I was using a hackable smartphone then and had written some custom stuff that wouldn't work on a modern smartphone to make keeping track of amounts and adding them up at the end easier. I'm not sure if there are any good apps for that kind of thing now-a-days. It would be cool if you could scan UPC barcodes with your phone and it would remember how much that item was from last time you bought it (though you could correct it if the price had changed since then.) That was something I was hoping to add to my system back when I was using it, but never got it done.
But, once I had a cart full of things and how much each cost, I could more easily weigh the value to me against the cost and make decisions about what to leave out that I was happier with later than if I guessed vaguely ahead of time.
What I used to do is to actually keep track of how much money worth of groceries are in my cart. Eggs go in the cart, put $1.69 in my smartphone. A bag of pistacios - $9.95. And then when I had everything from my list in the cart (plus maybe some potential impulse purchases) I'd add it all up. If my budget was $150 and when I added it up it was more than $150 (which was usually the case) I'd put things back on shelves until I got down to my budget. (These figures are 1) U.S. dollars, 2) don't include tax, 3) from quite a few years ago, 4) poorly remembered, and 5) for a family of 3 (plus two dogs). So don't freak out if these figures don't match up with what you think reasonable figures for you might be.)
I was using a hackable smartphone then and had written some custom stuff that wouldn't work on a modern smartphone to make keeping track of amounts and adding them up at the end easier. I'm not sure if there are any good apps for that kind of thing now-a-days. It would be cool if you could scan UPC barcodes with your phone and it would remember how much that item was from last time you bought it (though you could correct it if the price had changed since then.) That was something I was hoping to add to my system back when I was using it, but never got it done.
But, once I had a cart full of things and how much each cost, I could more easily weigh the value to me against the cost and make decisions about what to leave out that I was happier with later than if I guessed vaguely ahead of time.