I rarely even buy any cooking oils now. I cook occasionally in olive oil, though i am cautious with it because the smoke point is not very high. I cook bacon with no cooking oil (put it in a dry pan), then collect the rendered fat and then keep it in the fridge and use that for cooking.
Every now and then i cook a duck. I trim the extra fat and render the uncooked fat, and put that in the fridge. That is one of the best cooking fats, especially delicious with potatoes and root vegetables. When i roast the duck, i can collect the rendered fat from that, but that seems to be more brown and cooked, and doesn't keep as well and is more strongly flavored.
I bought some lard from free range pigs, and rendered that, and use that for cooking. It works well, kind of tricky because of high water content, duck fat is better. But a few pounds of lard go a long way.
When i cook sausage, i find the resulting rendered fat to break down a bit and be thin and somewhat burnt, so i don't use that for cooking.
The ground beef i get is about 20-25% fat and i can put that in a dry pan and it cooks great. However, like the sausage, that rendered fat gets thin and burnt, i think it is breaking down, so i don't use that for cooking. I find that rendered beef tallow is not very good for cooking.