What's been the very best money-saving kitchen tool for you?

There are lots of kitchen tools that are simply essential for cooking, such as knives, pots/pans, measuring cups/spoons, mixing bowls, etc. But there are a few tools that many folks might think are non-essential, but having them save you so much money over time.

I did a Google AI search for money-saving kitchen tools and it suggested Soda Stream, bread maker, citrus juicer or reamer, immersion blender/food processor, digital food scale, instant read thermometer, reusable silicone storage bags/bowl covers, and a quality chef's knife.

From its list, I wouldn't buy a Soda Stream because we don't drink soda or sparkling water enough to warrant spending the money. I would see it as a toy. 

I do have an instant read thermometer that I use for making yogurt, heating liquids to a correct temperature for a recipe, making candy, caramel sauce, and preserves, and to test meat temperature. It is a convenience over old-fashioned methods, but I wouldn't consider it really money-saving for my uses. I would still make jam, jelly, candy, and cook meat, but would use methods like dropping a bit into cold water (for candy), or indications like sheeting off a spoon (for preserves),  coating a spoon for a custard, or wiggling the leg of poultry to test for doneness. The only true money saver would be using it for making yogurt. I don't know any other way to tell when the milk is at the right temperature to have a successful batch.

We have a second hand glass citrus juicer that comes out of the cupboard a few times per year. I wouldn't make more dishes with citrus juice if I had an electric juicer or a reamer.

A digital food scale has been on my want list for a while. It would be nice to weigh meal portions, both raw and cooked meat, dough for baking, flour and other baking ingredients. But this is a want for now. Would it save me money? It might for creating specific sized portions (preventing overeating or under-eating of more expensive ingredients or meals). I might also be able to bake a better loaf of bread if I could be more precise, or 3 uniform loaves of bread when I do a larger baking, instead of 1 large loaf and 2 smaller ones, as often happens.

I have both an immersion blender and a food processor, and yes, I do think both of those are money savers. I cook and process whole pumpkins every fall to make my own pumpkin puree for baking and smoothies. An immersion blender can save a lumpy batch of gravy or puree microwaved vegetable mixtures with stock for quick soups. Both are handy and save us money.

There's an appliance that Google didn't suggest, but that I would put at the top of my list of money-savers, a stand mixer with a dough hook. We've had two stand mixers during our (long) marriage. The first was my parents and handed down to me when we were first married. When it failed, we bought another one. Even paying "new" prices, I still believe this has saved us a bundle of money. I've baked between 3 and 5 loaves of bread every week for 11 years with this mixer. That's 2288 loaves of high-quality whole grain bread. If I saved only $1 per loaf, I saved $2288 with that mixer. And I use the mixer for other recipes as well. 

So, how about you? is there one kitchen tool that you feel has been the best money-saver compared to its original cost?