A Humble Quality-of-Life Improvement

Not every purchase really adds to one's quality of life, and some which really do are insignificant outlays. Some even save money in the long run. Remember your grandmother's bowl covers? For awhile they were available in the supermarket as disposable conveniences but were taken off the market, presumably because consumers reused them too faithfully and hence repeat purchases were measly.
A few years back I bought some organic broccoli which was wrapped in such an elastic cap, and I reused this cover constantly. When it died, I set about tracking more down online. I googled every description I could think of, eventually learning that they're called "shower caps" in the produce biz. However you have to buy them buy the 1000's. Finally I found them for retail sale under the humble title of "bowl cover" - 50 sell for $4.99. They work better than cling-style wrap, are washable (you can throw them in with a load of wash and they survive intact), and endlessly reusable. And since they are clear (I seem to remember the 1950's version having little cherries and banana designs), you can easily see what leftover you've saved, increasing the chances you might really eat it. It is a small investment in sustainability, but a big improvement in daily life. (As one of my friends says, you can decrease your contribution to global warming by .000000001003672 % or so!)