This family is excellent at keeping costs down. They grow their own food, use solar power, buy second-hand clothes, and use biodiesel. They don't need to worry if energy prices go up.
I don't take detailed notes of what I spend my money on (I plan to start actually taking note of what I spend) but I have made the following estimates:
By far my biggest costs are the cash I pay to may parents as informal payment so that they in return let me live in their house and food. Food is really an area where I can cut a lot of fat because this food cost is actually due to me eating out at work at restaurants. I could get my parents to make me food from home but the food they make does not taste good. I don't blame my parents for making bad food for me because it is not their responsibility nor do they necessarily have much incentive to do so. I am trying to cut costs and as such I should expect poorer quality goods. It is also difficult for me to decline an invitation by co-workers to eat out because I have packed my own food from home. The type of people I am friends with at work like to eat out.
One strategy I have adopted to reduce food costs is to never buy any drinks and to drink water instead. I really hate it when restaurants serve disgusting water in disgusting cups. In order to be hydrated I keep a water bottle on my desk and refill it with free water at work.
Nevertheless, I estimate my monthly cost of living currently to be around $555, which is pretty reasonable. I could probably do better. Passive income produces around $260 per month, so the shortfall is made up for with my income from work.