This one is even more financially beneficial than most people realize. Besides using less TP; a bidet also lessens risks of hemorrhoids and urinary tract infections. This can save you tens of thousands of dollars (if you're in the USA) on surgeries, doctors visits, labwork, and antibiotics.
I bought some decent hiking boots for a trip I had. Thought I wouldnt use them much, but they have become my go to shoes for any days that will have a lot of walking, feetsavers.
Another one was my glasses. Thought I had 20/20 vision but got tested on a whim and turns out I have astigmatism. Didn't even realize I had been walking around in 720p for years.