I made ketchup once. We had the ingredients and it seemed easier than driving to the store when we had run out and I needed some for a meal.
...I ended up going out and getting some anyway.
I make a lot of my own food but it's usually the stuff you can't really buy. I cook chicken breasts and then eat off of them for several days. I keep stuff around to make baked potatoes, salads, etc.. These are interspersed through my more prepared meals. Though lately I'm on a fish kick.
I do all of my own cooking... it doesn't really count to your question, though. I buy bread and stuff.