I'm sure there are errors in my math and assumptions, but I would bet that my general point is sound (economists: correct me if I'm wrong).
One of my great skills is being a black-belt grocery shopper. (Another, in case you are curious, is analyzing poetry.) I have never spent more than about $200/month for my family of 4. And, no, I don't use coupons (I'm too messy). And even though we eat a lot of beans (because we love them; because they are a superfood; because they are environmentally good--oh, and cheap), we eat lots of luxury items too. So last week, Mr FS and I dined on lamb: we had lamb twice, lamb stir-fry once, and then--oh bliss--Scotch Broth, which Miss Em, back from college, declared her new favorite soup.
Last night, we had Miss Em's former favorite shrimp and corn soup.
I buy in the seemingly bizarre way advocated by the couponing-help site The Grocery Game: buy a bunch when it's on sale. There, you don't have to subscribe to the Game, which costs a little bit of money. Anyway, my cart will have one week 20 coffees; another week 20 peanut butters, whatever. When you are a poverty-stricken beginner at this, you can buy 3 coffees or peanut butters. Anything is better than nothing.
So, according to the USDA, in 2010 a family of four spent--per month--$582 for the thrifty plan, $758 for the next one, then $948, then $1150.
OK, let's ignore inflation and compounding. The fact that we eat well on less than the food stamp allotment (!) over 20 years: around $400 a month (around $5000/year) over 20 years=$100,000! Hey, that's around the principle on my house. Which I paid off early, btw. Now I see how.
Little savings over many years matter a lot. And really add up. That's good news for those of us who can't (or don't want to) find ways to earn more money.