A quick point to add. Adding fat to your meal makes it more filling and for longer. The worst fats are trans fats, second worse are polyunsaturated fats, and mono seem to be fairly good along with most saturated fats. In terms of cost some of the vegetable fats are much cheaper but they often have trans fats which are essentially toxic and they also go rancid very easily.
Saturated fats are generally solid at room temperature and don't absolutely need to be refrigerated on cool to moderate weather days. If you would sweat the butter would too, so put it in the fridge.
If you add a small amount of mince to your beans it will stretch really far and add tonnes of flavour and protein without breaking the bank. Cheaper mince comes with more fat but if you are making beans you want that, so get the cheaper mince, lean is not helpful.
Beans on rice freezes well for weeks. Beans without rice is good for months frozen. Beans with rice and any cheese or sour cream is not OK frozen. Beans with cheese microwaves well, but add sour cream after heating.
To make it more satisfying you can add a little bit of some chilli sauce. Hotter sauces go further, but the best is fermented sauces. The cheapest chilli sauces are full of sugar and water, so they just sweeten and dilute rather than flavour your dish.
If your beans tastes sour add a small amount of sugar, stir for a minute, and test again. Sugar fixes the sourness quite well.
For extra flavour a stock cube can be added. I would recommend beef stock for beans, but it will work with chicken or fish too. Most stocks are now vegan because they re synthetic, but they add a lot of flavour and are perfectly fine to eat.
The best option if you can manage it is to learn how to make a beef broth from bones. You boil the bones for hours, around 8 or so should do, and the bones will start to soften and become translucent. At this point all the nutritional goodness of the bones is in the broth. You can then use this as a base for making stew, beans, soup, etc, or you can reduce it by open top heating it and letting the steam leave. This will make a strong stock you can use to add flavour and nutrition to other meals for the cost of some energy and cheap bones.
A slow cooker can make cooking all of this much easier and safer. Electric slow cookers are able to be set up in the morning and have dinner most of the way ready by dinner time. The slow steady heat is great for bones and for softening meat and the easy of use is just fantastic.