There are a lot of elements of that lifestyle that you can do for pretty cheap. As others have mentioned, making your own granola isn't very expensive or difficult.
Actually getting outdoors is probably the hardest part, depending on where you live, available transportation, and your abilities. Hopefully there's somewhere nearby you can hike for free, and camping can be pretty cheap if you split the costs across a group and keep it simple (overnight tenting in the summer, someone has a car to get you to a campground). Again depends on where you are.
There are a lot of elements of that lifestyle that you can do for pretty cheap. As others have mentioned, making your own granola isn't very expensive or difficult.
Actually getting outdoors is probably the hardest part, depending on where you live, available transportation, and your abilities. Hopefully there's somewhere nearby you can hike for free, and camping can be pretty cheap if you split the costs across a group and keep it simple (overnight tenting in the summer, someone has a car to get you to a campground). Again depends on where you are.