I think the greatest thing since sliced bread are crock pots. With some extra time and preparation you can make them even more convenient to use.

I keep medium sized freezer bags filled with equal parts of coarsely chopped onions, carrots, and celery. Then I go to a bulk store and spend a few hundred dollars on meats of all kinds. We especially love beef stews. Then when we get home, I portion the meats into one pound servings and freeze. I also use this time to cut up pot roasts into stewing cubes cause it is cheaper to do this than to buy stewing cubes.

Then when you are ready, you just put in your beef broth, rip open the veggies bag and dump the veggies in and put in the thawed stewing cubes. I don't worry about using the veggies from a frozen state because I let mine simmer on high for an hour to kill bacteria. If you are using dried herbs, toss them in one hour before the stew is finished. It takes five minutes and supper will be done 8 hours later with almost no involvement from you

I find this saves me money numerous ways.
1. Veggies don't go bad before we get around to eating them because they are frozen
2. Dinner only takes 5 minutes of prep time so it saves me from saying "ugh I don't wanna cook. Lets just order pizza."
3. You can use cheaper cuts of meat because the crock pot makes it all so tender and palatable.
4. Crock pots use less in the way of utilities than stoves and ovens do. Such a bonus in the summer when you don't wanna heat up the house.

Some other benefits are that I don't have to spend much time in the kitchen cooking, and dinner dishes are a breeze without tons of pots, pans, cutting boards, knives, strainers, etc... to wash.

It's been a HUGE money saver for us.