Back in the day I occasionally head off into the national forest for two and three day trips with nothing but the clothes on my back, a mussette bag (actually a USGI gasmask bag) with assorted small stuff, SAK, two canteens (one with canteen cup), 6'by8' tarp/rain cape, water repellent jacket.

Rations were instant oatmeal (2/day), granola bars (4/day), Kipper snacks (1/day), M&Ms (1/day), instant coffee (3/day), and tea (3/day).

I would heat water two or three times a day with a tiny twig fire if allowed or use heat tabs.

I carry in two quarts water and have a tiny bottle with a dozen USGI iodine based water treatment tablets and a bandana to use as a sediment filter so I could resupply from creeks and ponds.

In the fall I would add a wool blanket but spring and fall I could just curl up and sleep soundly.

Total weight was under fifteen pounds and I almost always had excess food. Total cost, if I had to buy equivalents new, would be under $70.