I think slow cookers (aka Crock Pots) are the main small appliance that people think of when they think of frugal kitchen helpers. After all, a good one costs under $40 and will provide decades of service.
Did you have one growing up? Ours was the classic tall Rival Crock Pot in beige and brown. My parents used it to make chili and baked beans. My grandmother's was avocado green. Slow cookers definitely reflect the current kitchen trends; mine is black and stainless steel.
How do slow cookers save money? Some people think it is because they use very little energy compared to using stoves and ovens, but this isn't always true, as this article at Dollar Stretcher explains.
I think slow cookers save money in two specific ways. One, they don't heat up the house the same way using the stove top of oven does; for me this makes a difference in the heat of summer as I have noted that using my oven for a couple of hours will increase my air conditioning usage for the same hours. Some people use their slow cookers outside to reduce even the small amount of heat produced.
The other way slow cookers save money -- the biggest factor in my opinion -- is that they create convenience. If a person or family is going to be away from home and return at meal time the slow cooker can be set up to have that meal ready to eat, thus eliminating the temptation to eat out or resort to high priced convenience foods.
For families of all income levels, cutting restaurant and fast food meals is one of the quickest way to reduce the overall budget (and to increase health).
Family dinner and saving money are both important to me. When T played baseball and had 5PM games I would have the slow cooker going so that we would have dinner when we arrived home around 7PM. I used it when we went on field trips or day outings as a family. I even took it on vacation with us so we could spend the day on the beach and eat a home cooked meal when we returned to our condo.
Before I had my Instant Pot (more on that in another post) I would soak beans the night before and set them to cook in the morning, resulting in a cheap and healthy meal. My family enjoys pinto beans cooked with garlic as a simple bean soup, augmented with avocado, rice, vegetables, and/or salsa depending on the person and what we have available that day.
The convenience would continue, as I could mash the leftover beans in refried beans and use them in tacos or a casserole later in the week. The leftover bean broth could be used as the base for another soup.
Many other dishes can be cooked in the slow cooker; when we ate meat we often used the slow cooker to gently simmer tougher (less expensive) cuts of meat into tender delicacies. I won't go into details but will suggest that anyone who is interested check out Stephanie O'Day's website, A Year of Slow Cooking.
Because of my Instant Pot my slow cooker doesn't see much action these days; I keep it tucked away for occasions where I will be cooking for a crowd and need multiple ways to cook and keep foods warm. This is another way a slow cooker saves me money; I can entertain by serving simple, inexpensive dishes. One thing my friends really like it to come over for a soup supper. I will make two or three soups along with bread and a cabbage salad, and keep the soups warm all evening using my slow cooker, Instant Pot, and vintage electric Dutch Oven (coming up soon, a post on vintage kitchen electrics!).