I do lots of that sort of thing, you are not alone. DBH is a food snob, so I often buy cheap stuff and pop it in bags from somewhere else, he never notices. If I should die suddenly, he is going to wonder how on earth I ever managed to feed us as cheaply as I do. I used to do the soya mince things decades ago, it was so much cheaper. Now we rarely eat mince, but I buy very cheap coffee, make my own washing liquid but put it in old containers after he said mine wasn't as good, decant cheap biscuits into jars so that he won't notice, all that sort of thing. My very best one I think was when I cut out the Tesco labels in his new white shirts and sewed in some M&S ones I had saved for the purpose.