On a similar note to what @lagomorphlecture@lemm.ee I have an instant pot and that's made cooking stuff that's cheap but usually takes time to make really easy, brown rice or a potato based soup are a click away. At of course the cost of an upfront investment.
Also, some recipes can be really cheap if you have the time. Rossotto, homemade bread (with yeast or baking soda), baked beans (from dry bulk pinto beans), pasta (homemade & store bought) naan bread & homemade wheat tortillas, and baked oatmeal are all things I enjoy that come to mind and might be worth trying. They taste good and can be made for super cheap.
I'm a vegetarian and my instant pot is great for beans. I didn't bring that up since canned beans are cheap but they're high sodium and are probably more contaminated with plastic than dried beans. I would never bother with dried beans without the instant pot but they're super easy with it. So I guess depending on your diet either an instant pot, slow cooker or air fryer can really have a huge impact on your grocery bill.
Part of it probably depends on what beans. I eat a lot of chickpeas and I think they're a harder bean and less likely to get mushy. The other one is black beans and definitely they would be easier to overcook. Did you do the quick release? If not, next time quick release then immediately drain them and give them a quick rinse in cold water. I'm just using the bean setting on my instant pot so if that's what you're doing and it's still mushy with the quick release, figure out how long that cooks for and drop it by a minute or two.