Frugality is not just about reasonable economic return on investment. For me, the philosophy runs much deeper. It is about the societal bargain in which many of us participate. Some people give me the 'crazy person' stare when I share my philosophy, but here goes.
We working people have some skill needed by someone else. The 'someone else' is willing to trade their stuff for your time and energy. Your time and energy make up a slice of your life that you will never get back. The 'stuff' most of us receive for that slice of our life is called 'money,' so in a very real sense we working people legally sell slices of our life for money. I don't take that literal interpretation lightly. My money represents the hours I toiled and won't get back, so I try to use them thoughtfully, or frugally.
For me, this is a guiding concept when I spend money. If you make $20 an hour, is it worth 6 or 8 hours of YOUR LIFE to buy the cool sneakers for your 9 year-old? Certainly your choice, but for me the answer is an immediate NO. Is it worth 6 or 8 hours of my life to buy a small portable solar electric system with LED light that I can use for multiple purposes including emergency preparedness when it's on sale for half price? That one I'll certainly consider.
When I spend 20 minutes to find the least price for an item that will save me $10 per item and I need 3 of them, I've paid for my time by being frugal. If I decide on an item, I may even wait several months (or years) for a clearance or special sale to buy it. It's all in how much value I place on the trade. If quick research shows that shopping around may save me $5 on the total of 3 items, I'll save my time and money (as a 'bank' of my time and energy) for higher purposes.
If you are currently blessed with more time than money, then consider low cost ways of converting your time into what you need. See if there are ways locally to bypass the 'converting to and from money' phase. Neighbor with a huge garden? Do you have real skills to trade for veggies? What are your unique skills? I have a neighbor who is the world's most fabulous housekeeper and stay-at-home Mom. This time of year she wants to buy her husband a Christmas present without him paying for it. She trades a few hours of her skill to help me spruce up for the holidays. We are both thrilled. We trade each other pieces of our lives for a fair exchange of high-quality requirements. She thinks I trade her more than her skill is worth. I have someone I truly trust come into my home to help me, which is worth more than gold to me. To me, that's the essence of being frugal.